It's impossible to remove unused filesystem pools from a cluster
We've inadvertently made it impossible to remove a filesystem from a Ceph cluster. If there is not data in the FS, it should be possible to remove the final data pool and metadata pool.
One option is to extend the "news" command to create a "blank" FS that doesn't contain anything.
Revert "mon: OSDMonitor: Refuse to delete CephFS pools"
This reverts commit c7d265a9b276aad5caf9b35f3ce8bc7bdd169f0f.
Because this pre-dates the `fs rm` command, this change was
preventing firefly users from ever deleting their filesystem pools.
Signed-off-by: John Spray <email@example.com>