LU-17057 tests: Fix sanity-sec/0

LU-17057 tests: Fix sanity-sec/0

Command executed through 'runas' on failure breaks
out of running test script. While this failure is
expected. The setting of 'set -e' forces the pipeline
to exit the running script immediately. This patch
fixes this by checking the return value and then
taking the appropriate action.

This patch also fixes 'touch' command to file f4 by
correctly calling it via uid and gid as it was set
few lines above.

Test-Parameters: trivial testlist=sanity-sec env=ONLY=0,ONLY_REPEAT=100
Signed-off-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Change-Id: I06e6d22840e31add8c24cf90c31b98464d580ae7
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53194
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>