Add test for compaction age changes to elasticity

[DomGarguilo]

In #4667, a test was added to make sure the compaction duration was not reset when the coordinator restarted. These changes have been merged up from 2.1 into main (8c99aff). When merging from main to elasticity there are some more major differences that made merging that test case too difficult without making big changes.

This ticket exists to make sure that this test case is added back into elasticity.