LU-9272 tests: fix for facet_failover mgs

LU-9272 tests: fix for facet_failover mgs

Have facet_failover to work for mgs facet and include failover
nodes in the list of nodes to load modules.

When mgs/mds are combined, assign the failover host of mds to
the failover host of mgs.

Assign mgsfailover_dev with mds1failover_dev when mgs/mds are combined
while mounting facets, as mds1failover_dev is already defined when
mgs/mds are combined.

Fix start() to export mgs_dev and mgsfailover_dev for
combined_mds_mgs.

Do not wait recovery complete on mgs.

Test-Parameters: trivial failover=true osscount=2 mdscount=2 mdtcount=1 austeroptions=-R iscsi=1 env="ONLY=121" testlist=conf-sanity
Test-Parameters: testlist=conf-sanity
Change-Id: Ie698814c530c8deb98aa0010f2a0fa8e261b4b69
HPE-bug-id: MRP-3374, LUS-4858, LUS-2361
Signed-off-by: Elena Gryaznova <c17455@cray.com>
Signed-off-by: Alexander Boyko <c17825@cray.com>
Signed-off-by: Noopur Maheshwari <noopur.maheshwari@seagate.com>
Signed-off-by: Vladimir Saveliev <c17830@cray.com>
Signed-off-by: Alexander Zarochentsev <alexander.zarochentsev@hpe.com>
Reviewed-on: https://review.whamcloud.com/26235
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Elena Gryaznova <elena.gryaznova@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>