LU-18114 llog: split "lctl llog_*" group into subcommands

LU-18114 llog: split "lctl llog_*" group into subcommands

Split "lctl llog_*" command group into subcommands, e.g.
"lctl llog_info" to "lctl llog info".
Also, conf-sanity.sh test_123ad is modified to verify
this patch.

Signed-off-by: Emoly Liu <emoly@whamcloud.com>
Change-Id: Iea1cbfac61ff807d793a7a48dafa73915b06639d
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56040
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Zhenyu Xu <bobijam@hotmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>