Fix WOPI thread abusive naming

The threads handling the WOPI requests, matching "/files/{fileId}", are prefixed with "WOPI_" to be clearly identified. See https://github.com/nuxeo/nuxeo/blob/v11.5.142/modules/platform/nuxeo-wopi/src/main/java/org/nuxeo/wopi/jaxrs/WOPIRoot.java#L66.

Yet, once the request is over, the thread name is not set back to its original name, so  the thread might return to the pool with an irrelevant name.

This is an issue for the ops review process as we suspect that some threads are marked as WOPI whereas they aren't necessarily related to WOPI requests.