LU-9444 tests: replace SINGLEMDS1 with SINGLEMDS

LU-9444 tests: replace SINGLEMDS1 with SINGLEMDS

In conf-sanity test 87, we use the global variable SINGLEMDS1
to get the version of the MDS. SINGLEMDS1 is not defined and
the test should use SINGLEMDS to check the version of the MDS.

Test-Parameters: trivial testlist=conf-sanity
Test-Parameters: envdefinitions=ONLY=87 mdsjob=lustre-b2_9 ossjob=lustre-b2_9 serverbuildno=22 testlist=conf-sanity
Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: Ic8b1f32b87cc596fcc2e98d5b6095b6e4171bfd7
Reviewed-on: https://review.whamcloud.com/31420
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Wei Liu <wei3.liu@intel.com>
Reviewed-by: Saurabh Tandan <saurabh.tandan@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>