LU-17675 tests: disable sanity-flr/61a on RHEL9.3

LU-17675 tests: disable sanity-flr/61a on RHEL9.3

still failing a lot:
Error: 'f61a.sanity-flr: atime: old '1712732591' != new '1712732585''
Failure Rate: 32.61% of most recent 92 runs, 8 skipped (all branches)

Test-Parameters: trivial
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: Id1b97d884f83b743a9ca6e72d21237689b5d19be
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/54731
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>