LU-18882 tests: sanity/56ca to reset readonly and wait

LU-18882 tests: sanity/56ca to reset readonly and wait

sanity/56ca should wait till readonly=0 is propagated,
otherwise few subsequent tests may find OST0000 read-only
and fail.

Fixes: 51c4e89318 ("LU-18833 ofd: Set OS_STATE_* flags correctly for read-only devices")
Test-Parameters: trivial
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I7767c0ec932395e127ffb53fd91f9af182a34b40
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58635
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>