gitlab-ci: Do not retry for job_execution_timeout

gitlab-ci: Do not retry for job_execution_timeout

If we timeout, we should just stop at 2 hours, not waste 6 hours (3 x 2 hours).

This is for when the job runs long for any reason, currently the
reasons for a timeout are not transient, we need to either change
the timeout or fix the system.  Likewise if the tests get into a loop
or deadlock we want to see that as a failure.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14863

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>