Refactore Tests for AbstractTaskanaJob#initializingSchedule

[arolfes]

These 3 tests do exactly the same thing. During the refactoring, the logic was moved to AbstractTaskanaJob, but the tests were not adapted. Please do so here.

• HistoryCleanupJobAccTest#should_DeleteOldHistoryCleanupJobs_When_InitializingSchedule()
• TaskCleanupJobAccTest#should_DeleteOldTaskCleanupJobs_When_InitializingSchedule
• WorkbasketCleanupJobAccTest#should_DeleteOldWorkbasketCleanupJobs_When_InitializingSchedule

[mustaphazorgati]

In #2239 some further tests have been moved to AbstractTaskanaJobAccTest. Please refactor them before moving/refactoring the tests into that class. Thanks!