Automatic merge from submit-queue (batch tested with PRs 43355, 42827)
[Federation] Rewrite ReplicaSet CRUD and Preferences tests.
I think `should create replicasets and rebalance them` test is still flaky. I still don't know the source of this flakiness. I will continue hunting. But it is a lot less flaky than before (or perhaps it even never passed before?). This PR could be merged now and flake hunting can happen in parallel.
```release-note
NONE
```
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