LU-13271 tests: skip 87, 115 tests if FILESET set

LU-13271 tests: skip 87, 115 tests if FILESET set

When FILESET is set the tests require Lustre root mounted
on $MOUNT are to be skipped.

Test-Parameters: trivial testlist=conf-sanity envdefinitions="FILESET=/subdir" envdefinitions=ONLY=87
Test-Parameters: testlist=conf-sanity envdefinitions="FILESET=/subdir" envdefinitions=ONLY=115
Signed-off-by: Elena Gryaznova <c17455@cray.com>
Reviewed-by: Vladimir Saveliev <vladimir.saveliev@hpe.com>
Reviewed-by: Alexander Boyko <alexander.boyko@hpe.com>
Change-Id: I8931d0419d3613caf53497c99ad8185dc2b56fad
Reviewed-on: https://review.whamcloud.com/37647
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Vladimir Saveliev <c17830@cray.com>