monitor_testcase_14: make script executable

Signed-off-by: Hannes Reinecke <hare@suse.de>
monitor_testcase_13: Enable -o errexit for increased safety

Immediately terminate the script upon any failure.  Prevent math expression
evaluation from failing the test.

Signed-off-by: Libor Pechacek <lpechacek@suse.cz>