migrate log4j test configuration to log4j2

since NXP-23863, nuxeo is running log4j2. as a side effect, our own configuration for tests aren't use anymore. Also, we've seen nuxeo is distributing log4j2-test.xml in core modules, which mask the problem to consumers.

We need to cleanup:

• Delete existing log4j.xml if not necessary
• Rewrite required files to log4j2.yml format