Remove module 'run-all-junit-tests' from root POM -> speed up the build

Remove module 'run-all-junit-tests' from root POM -> speed up the build

This module must be a relic from a test runner module once existing
during the Ant build era, but transferred and kept alive in the Maven
build. Actually, it almost doubles build time by running virtually all
tests in all modules again when doing 'mvn test' from the project root.

For now I only removed the module from the root POM, leaving behind
comments there, in the module POM and in the now @Deprecated class
RunTheseBeforeYouCommitTests.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>