LU-9494 test: Improve message for skipping tests

LU-9494 test: Improve message for skipping tests

Modify skip messages for consistency and clarity.

Lustre-change: https://review.whamcloud.com/27350
Lustre-commit: 75b426f9f9d3f21e08cd1e62b7fa4962a2b8c679

Test-Parameters: trivial testlist=sanity

Signed-off-by: Ruth Klundt <rklundt@sandia.gov>
Change-Id: I44ced56e67aa63ed84da6a15c88282bc3ff19332
Reviewed-by: Wei Liu <wei3.liu@intel.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Signed-off-by: Minh Diep <minh.diep@intel.com>
Reviewed-on: https://review.whamcloud.com/28522
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>