moveCollection will currently try to use any existing zones for a nss and try to build tags docs for these zones. Zones can only be used with sharded collections, but a user can create zones for a non-existing sharded collection that shares the same namespace as an existing unsharded collection. These zones won't be used in balancing activities after a moveCollection. But moveCollection might fail when trying to add a tag doc for these zones. So in the unlikely scenario that a user has created a zone on a namespace for which they have an existing unsharded collection, we should skip the zone checks.

Due to this being an unlikely situation, I am not marking this as 8.0 required.