LU-9411 tests: remove spaces around '+='

LU-9411 tests: remove spaces around '+='

In sanity test 27D, the variable that collects tests to
skip needs to have spaces removed when the variable is
being concatenated with new tests to skip.

Test-Parameters: trivial

Lustre-change: https://review.whamcloud.com/30725
Lustre-commit: ecc770c3435b8dc277f7b7606e93f22d2c6a6069

Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: Ie57efecd2867b748f56998bc2fc375ea9d566611
Reviewed-by: Saurabh Tandan <saurabh.tandan@intel.com>
Reviewed-by: Wei Liu <wei3.liu@intel.com>
Reviewed-by: Cliff White <cliff.white@intel.com>
Signed-off-by: Minh Diep <minh.diep@intel.com>
Reviewed-on: https://review.whamcloud.com/31112
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>