NamespaceString::checkLengthForFCV returns true if the namespace length is valid for the FCV setting added in
SERVER-41745. Need to clean up the callers of checkLengthForFCV, too.
Looks like jstests/multiVersion/long_collection_names.js can be removed.
Please check the SERVER ticket(s) that added the FCV gates for anything else incidental to remove, particularly any testing that can be deleted.