LU-9899 tests: mount client on MGS for ost-pools

LU-9899 tests: mount client on MGS for ost-pools

When a Lustre configuration has the MGS and MDS on separate
nodes, the file system must be mounted on the MGS to allow
OST pools to work properly.

Add the ability to mount the file system on the MGS when
necessary for the Lustre test suite ost-pools.sh.

Test-Parameters: trivial testlist=ost-pools
Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: Iff0663a38b92bb8e71c313897b12fca98fdae932
Reviewed-on: https://review.whamcloud.com/28638
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Arshad Hussain <arshad.hussain@seagate.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
(cherry picked from commit bb4c3bc38eeeeec111c14c024669465addb30c70)
Reviewed-on: https://review.whamcloud.com/30215
Reviewed-by: Arshad Hussain <arshad.super@gmail.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>