squid: mds: add missing policylock to test F_QUIESCE_BLOCK

squid: mds: add missing policylock to test F_QUIESCE_BLOCK

In order to check an inode's F_QUIESCE_BLOCK, the quiesce_inode op must acquire
the policylock. Furthermore, to ensure the F_QUIESCE_BLOCK is not changed
during quiesce, the lock must be held for the duration of the op's lifetime.

Fixes: https://tracker.ceph.com/issues/65595
Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
(cherry picked from commit 50613b5562469ad24ed0fc547cafcfdeef5be604)
Fixes: https://tracker.ceph.com/issues/65740