mds/quiesce: don't take mirrored cap-related locks on the replica

mds/quiesce: don't take mirrored cap-related locks on the replica

For every mirrored lock, the auth will message the replica to ensure
the replicated lock state. When we take x/rdlock on the auth, it will
ensure the LOCK_LOCK state on the replica, which has the file caps we
want for quiesce: CACHE and BUFFER.

It should be sufficient to only hold the quiesce local lock
on the replica side.

Signed-off-by: Leonid Usov <leonid.usov@ibm.com>