SERVER-96828 introduced a bug when the DropDatabase coordinator ran on a mixed binary version scenario.

This was solved by SERVER-97830 preventing the insertion of a document in kConfigDropPendingDBsNamespace whenever the sharded cluster is being upgraded or downgraded.

SERVER-97830 introduced a new problem: a CreateDatabase operation may not properly serialize with a DropDatabase when there is an upgrade in progress.

The following sequence of events exemplifies the issue:

1. An upgrade starts.
2. A DropDatabase operation starts and it doesn't insert a document in kConfigDropPendingDBsNamespace because the CreateDatabase feature flag is not enabled yet
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   .

3. The upgrade process finishes, therefore the CreateDatabase feature flag is enabled. The DropDatabase operation hasn't finished yet.
4. A CreateDatabase operation starts instantiating the new coordinator. It checks if there is a concurrent drop database
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   , the check passes although there is a concurrent DropDatabase coordinator.