Currently, the resharding_donor_service_test.cpp and resharding_recipient_service_test.cpp have stepdown tests that rely on mocking the coordinator's state changes to make progress.

Issue: The loop iterating over which states to pause and then stepdown upon mocks incorrect behavior - it can mock a coordinator's transition to kBlockingWrites before the donor itself is in kDonatingOplogEntries.

Example:
. state = DonorStateEnum::kDonatingOplogEntries  in the test loop

. at the start of this iteration, ReshardingDonorDocument.state = kDonatingInitialData on disk

. the test mocks the coordinator's transition into kApplying
. the donor finishes up all the necessary work and is ready to transition to 'state' kDonatingOplogEntries

. the test waits until the OpObserverForTest::onUpdate witnesses attempt to transition to kDonatingOplogEntries
. the test calls stepDown, causing the OpObserverForTest::onUpdate to throw when the opCtx is interrupted and the write ReshardingDonorDocument.state = kDonatingOplogEntries fails

 . (next iteration) state = DonorStateEnum::kBlockingWrites, but ReshardingDonorDocument.state = kDonatingInitialData still
. The test mocks the coordinator's transition to kBlockingWrites, before the donor is in kDonatingOplogEntries, which is illegal in the real system

Note:
We want to preserve the behavior that the stepdown occurs before the participant persists its new state to its local ReshardingDocument.