The MDS mds_standby_for_*, mon_force_standby_active, and mds_standby_replay
configuration options have been obsoleted. Instead, the operator may now set
the new "allow_standby_replay" flag on the CephFS file system. This setting
causes standbys to become standby-replay for any available rank in the file
system.
Closes: https://github.com/rook/rook/issues/2768
Signed-off-by: Sébastien Han <seb@redhat.com>