In suites that run add/remove shard in the background without the balancer enabled, the test hook will manually move collections off the draining shard. If the collection is untracked, then the reshardCollection coordinator will not throw on throwIfReshardingInProgress when registering the index build, and instead the reshard collection will fail later during the applying phase with OplogOperationUnsupported. This error is transient, and the test hook can just retry on this error.