LU-18114 barrier: split "lctl barrier_*" group into subcommands

LU-18114 barrier: split "lctl barrier_*" group into subcommands

Split "lctl barrier_*" command group into subcommands, e.g.
"lctl barrier_freeze" to "lctl barrier freeze".
Also, sanity.sh test_801c is modified to verify this patch.

Signed-off-by: Emoly Liu <emoly@whamcloud.com>
Change-Id: Ibccc0206bae6ef0fa8efd744b46c7f864aa42cbe
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56107
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Frederick Dilger <fdilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>