LU-8621 utils: cmd help to stdout or short cmd error

LU-8621 utils: cmd help to stdout or short cmd error

- Changed to print command help to stdout
- Changed to output short error message for an unrecognized command

Lustre-change: https://review.whamcloud.com/47162/
Lustre-commit: bc69a8d058f5bcdb75e062df57a6ccd23243d1e0

Test-Parameters: trivial
Signed-off-by: Aleksei Alyaev <aalyaev@ddn.com>
Change-Id: I67616ddb576e3347a2da130b3a731a6bf8730185
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/48851
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>