It is a follow-up to JENKINS-55199 and https://github.com/jenkinsci/plugin-compat-tester/pull/102

The implemented patch is far from being ideal, because the bogus dependency gets removed from the effective plugin POM. It should never get there in the first place.

Acceptance criteria:

• PCT splitDependencies() logic is refeactored so that the self-dependency is not added to the POM file
• The hack from https://github.com/jenkinsci/plugin-compat-tester/pull/102 is removed