Major Description
Now that Kudu automatically adds a master if we start up a new master alongside an existing only set of masters, we should also loosen the restriction that the gflag is the same as the existing Raft config, in case users want to add a master and then restart the entire cluster at the same time.
This seems like it would be common enough for orchestration tools like CM, which marks the cluster as stale and suggests a full service restart upon adding a new master role.