Unit test for Kafka admin deletedMessagesCalled() fail

There is a intermittent failure in TestRepartitionJoinWindowApp.testRepartitionJoinWindowAppWithoutDeletionOnCommit() due to the flag deleteMessagesCalled is always set and SystemAdmin.deleteMessages() is always called in TaskInstance.commit(). Hence, when the auto-commit is triggered in the test, the assertion in the unit test will fail.

The fix is to set the deleteMessagesCalled flag only when the actual delete action is invoked.