In collection_defragmentation.js, we wait for defragmentation to finish, enable balancing, wait for balanced, and then reenable defragmentation. After reenabling defragmentation, we wait for it to complete and then check the defragmentation state. However, since balancing is still enabled, migrations can happen between defragmentation finishing and the final state checks happening.

We should re-disable balancing after waiting for the collection to be balanced.