Fix LogTestWatchman usage in functional tests

[INFO] Running org.nuxeo.ftest.server.ITStartupPageTest
2020-04-22 03:57:31,004 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITStartupPageTest#testStartupPage'
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 7.412 s - in org.nuxeo.ftest.server.ITStartupPageTest
[INFO] Running org.nuxeo.ftest.server.ITOAuth2Test
2020-04-22 03:57:36,906 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITOAuth2Test#testAuthorizationDenied'
2020-04-22 03:57:39,813 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITOAuth2Test#testAuthorizationErrors'
2020-04-22 03:57:41,563 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITOAuth2Test#testAuthorizationOnCMIS'
2020-04-22 03:57:44,730 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITOAuth2Test#testAuthorizationOnRestAPI'
2020-04-22 03:57:46,682 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITOAuth2Test#testOAuth2GrantPage'
2020-04-22 03:57:47,737 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITOAuth2Test#testAuthorizationWithAutoGrant'
2020-04-22 03:57:49,305 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITOAuth2Test#testAuthorizationSubmitErrors'
2020-04-22 03:57:52,596 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITOAuth2Test#testTokenGetRequest'
2020-04-22 03:57:53,120 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITOAuth2Test#testAuthorizationGranted'
2020-04-22 03:57:54,713 [main] WARN  [LogTestWatchman] Cannot log on server message: Starting test 'org.nuxeo.ftest.server.ITOAuth2Test#testAuthorizationWithExistingToken'
[INFO] Tests run: 10, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 20.293 s - in org.nuxeo.ftest.server.ITOAuth2Test
[INFO] Running org.nuxeo.ftest.server.ITRestAPITest
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.095 s - in org.nuxeo.ftest.server.ITRestAPITest
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 12, Failures: 0, Errors: 0, Skipped: 0

======================================================================
= Component Loading Status: Pending: 0 / Missing: 0 / Unstarted: 0 / Total: 539
======================================================================
2020-04-22T03:57:40,192 WARN  [http-nio-0.0.0.0-8080-exec-13] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Missing required field "client_id".)
2020-04-22T03:57:40,528 WARN  [http-nio-0.0.0.0-8080-exec-1] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Missing required field "response_type".)
2020-04-22T03:57:40,606 WARN  [http-nio-0.0.0.0-8080-exec-10] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=unsupported_response_type, description=Unknown response_type: got "unknown", expecting "code".)
2020-04-22T03:57:40,704 WARN  [http-nio-0.0.0.0-8080-exec-4] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Invalid client_id: unknown.)
2020-04-22T03:57:40,793 WARN  [http-nio-0.0.0.0-8080-exec-6] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Invalid redirect_uri parameter: unknown. It must exactly match one of the redirect URIs configured for the app.)
2020-04-22T03:57:40,884 WARN  [http-nio-0.0.0.0-8080-exec-11] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Invalid PKCE parameters: either both code_challenge and code_challenge_method parameters must be sent or none of them.)
2020-04-22T03:57:40,960 WARN  [http-nio-0.0.0.0-8080-exec-3] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Invalid PKCE parameters: either both code_challenge and code_challenge_method parameters must be sent or none of them.)
2020-04-22T03:57:41,056 WARN  [http-nio-0.0.0.0-8080-exec-2] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Invalid code_challenge_method parameter: transform algorithm unknown not supported. The server only supports [plain, S256].)
2020-04-22T03:57:49,767 WARN  [http-nio-0.0.0.0-8080-exec-5] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=The /oauth2/authorize_submit endpoint only accepts POST requests.)
2020-04-22T03:57:50,118 WARN  [http-nio-0.0.0.0-8080-exec-13] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Missing required field "client_id".)
2020-04-22T03:57:50,458 WARN  [http-nio-0.0.0.0-8080-exec-10] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Missing required field "response_type".)
2020-04-22T03:57:50,780 WARN  [http-nio-0.0.0.0-8080-exec-6] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=unsupported_response_type, description=Unknown response_type: got "unknown", expecting "code".)
2020-04-22T03:57:50,997 WARN  [http-nio-0.0.0.0-8080-exec-3] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Invalid client_id: unknown.)
2020-04-22T03:57:51,196 WARN  [http-nio-0.0.0.0-8080-exec-7] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Invalid redirect_uri parameter: unknown. It must exactly match one of the redirect URIs configured for the app.)
2020-04-22T03:57:51,509 WARN  [http-nio-0.0.0.0-8080-exec-5] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Invalid PKCE parameters: either both code_challenge and code_challenge_method parameters must be sent or none of them.)
2020-04-22T03:57:51,824 WARN  [http-nio-0.0.0.0-8080-exec-13] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Invalid PKCE parameters: either both code_challenge and code_challenge_method parameters must be sent or none of them.)
2020-04-22T03:57:52,109 WARN  [http-nio-0.0.0.0-8080-exec-10] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=Invalid code_challenge_method parameter: transform algorithm unknown not supported. The server only supports [plain, S256].)
2020-04-22T03:57:52,611 WARN  [http-nio-0.0.0.0-8080-exec-2] [org.nuxeo.ecm.platform.oauth2.NuxeoOAuth2Servlet] OAuth2 authorization request error: OAuth2Error(id=invalid_request, description=The /oauth2/token endpoint only accepts POST requests.)