Clean up Apache RAT configuration

[ppkarwasz]

Due to the RAT-355 enhancement, Apache Rat 0.16 is now able to implicitly ignore most files ignored by Git.

This allows us to clean up the configuration from all the files that are also in a typical .gitignore.

[ppkarwasz]

This issue is a no-op for logging-parent, but should be applied to logging-log4j2.

I am keeping this issue open until apache/maven-apache-parent#185 is merged and we bump to a new version of the ASF parent.

[vy]

@ppkarwasz, instead of waiting for the next org.apache:apache release, we can

1. override the org.apache.rat:apache-rat-plugin version ourselves
2. create an issue to remove the override once the next org.apache:apache release arrives
3. ship this in 10.6.0