Consider removing logging impl configuration from brave-tests

[iparadiso]

Describe the Bug

This isn't necessarily a bug, but rather an integration issue. We have a spring boot application that has on brave-tests on the test classpath. This module has a log4j2.properties, which is picked up by spring and caused some logging corruption between tests running in parallel on the same JVM. Removing this dependency resolved the issue.

We generally don't expect libraries to come with their own logging configuration opinions and to let the applications provide those opinions. Libraries should just use SLF4j API and let the application provide the impl and configuration.

Would you consider removing this log4j configuration from the library? Is it actually needed?