LU-12410 tests: ignore return status of removal of 99-lustre-test.rules

LU-12410 tests: ignore return status of removal of 99-lustre-test.rules

we don't care if we cannot remove it on th server side.

Change-Id: Id6833505c1e7cd39df9845a16b01c31c9d65e794
Test-Parameters: trivial
Test-Parameters: testlist=sanity-dlc
Signed-off-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/35398
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Chris Horn <hornc@cray.com>