LU-9213 scripts: check MGT status in lustre init script

LU-9213 scripts: check MGT status in lustre init script

This patch fixes health_check() in lustre init script to
account for the status of MGT on a dedicated node.

Test-Parameters: trivial

Change-Id: Ifdf2e4a1002e870c25925b6e7fce82b132cc24f2
Signed-off-by: Jian Yu <jian.yu@intel.com>
Reviewed-on: https://review.whamcloud.com/25995
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>