Harmonize log configuration

Prior to this commit, the codebase was using a mix of `log4j.xml` and `log4j.properties` for test-related logging configuration. This can be an issue as log4j takes the xml variant first when looking for a default bootstrap configuration.

In practice, some modules declaring the properties variant were taking the xml variant configuration from another module.

The general structure of the configuration has also been harmonized to provide a standard console output as well as an easy way to enable trace logs for the current module.