Fix repository cleanup on TestConnectionManagement tests

[CoreFeature] Unable to reset repository
org.nuxeo.ecm.core.api.NuxeoException: Cannot use a CoreSession outside a transaction
	at org.nuxeo.ecm.core.api.local.LocalSession.getSession(LocalSession.java:104)
	at org.nuxeo.ecm.core.api.AbstractSession.queryAndFetch(AbstractSession.java:1223)
	at org.nuxeo.ecm.core.api.AbstractSession.queryAndFetch(AbstractSession.java:1198)
	at org.nuxeo.ecm.core.test.CoreFeature.cleanupSession(CoreFeature.java:278)
	at org.nuxeo.ecm.core.test.CoreFeature.afterRun(CoreFeature.java:222)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$5.call(FeaturesRunner.java:187)
	at org.nuxeo.runtime.test.runner.FeaturesLoader.apply(FeaturesLoader.java:126)
	at org.nuxeo.runtime.test.runner.FeaturesLoader.apply(FeaturesLoader.java:113)
	at org.nuxeo.runtime.test.runner.FeaturesRunner.afterRun(FeaturesRunner.java:183)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$AfterClassStatement.evaluate(FeaturesRunner.java:287)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$RulesFactory$1.evaluate(FeaturesRunner.java:525)
	at org.nuxeo.runtime.test.runner.FeaturesRunner$BeforeClassStatement.evaluate(FeaturesRunner.java:268)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
	at org.junit.runners.Suite.runChild(Suite.java:127)
	at org.junit.runners.Suite.runChild(Suite.java:26)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)