LU-5863 tests: add a separate MGS/MDS test case into conf-sanity

LU-5863 tests: add a separate MGS/MDS test case into conf-sanity

In conf-sanity.sh, test 21d is a basic test case that verifies
separate MGS/MDS. However, it's always skipped under combined
MGS/MDS configuration. This patch adds a new test case 21e to
setup another Lustre filesystem to verify separate MGS/MDS without
depending on the configuration of the origial Lustre filesystem.

Test-Parameters: alwaysuploadlogs \
envdefinitions=SLOW=yes,ONLY=21 \
mdtfilesystemtype=ldiskfs mdsfilesystemtype=ldiskfs \
ostfilesystemtype=ldiskfs testlist=conf-sanity

Test-Parameters: alwaysuploadlogs \
envdefinitions=SLOW=yes,ONLY=21 \
mdtfilesystemtype=zfs mdsfilesystemtype=zfs \
ostfilesystemtype=zfs testlist=conf-sanity

Signed-off-by: Jian Yu <jian.yu@intel.com>
Change-Id: I3defa936a9b4f97dc3849c3a4a9626332da53d0f
Reviewed-on: http://review.whamcloud.com/13391
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>