Refactor the clean up logic implementation in security-command-center/snippets/src/test/java/management/api/EventThreatDetectionCustomModuleTest.java

[minherz]

Following the discussion in #9912, please refactor the clean up logic in the security-command-center/snippets/src/test/java/management/api/EventThreatDetectionCustomModuleTest.java:

• move the implementation into cleanUp() method; the method cleanupExistingCustomModules() is called only there
• refactor the implementation to delete *ONLY* custom modules created by the current execution of the test; the current implementation deletes custom modules created by all instances of the class that may run in parallel; a possible approach to collect created module IDs into a list and delete them at the end