gitlab-ci: Make more custom runner jobs manual, and don't allow failure

Currently we define a lot of jobs for our custom runners:
for both aarch64 and s390x we have
 - all-linux-static
 - all
 - alldbg
 - clang (manual)
 - tci
 - notcg (manual)

This is overkill.  The main reason to run on these hosts is to get
coverage for the host architecture; we can leave the handling of
differences like debug vs non-debug to the x86 CI jobs.

The jobs are also generally running OK; they occasionally fail due to
timeouts, which is likely because we're overloading the machine by
asking it to run 4 CI jobs at once plus the ad-hoc CI.

Remove the 'allow_failure' tag from all these jobs, and switch the
s390x-alldbg, aarch64-all, s390x-tci and aarch64-tci jobs to manual.
(We keep -all on s390x and -alldbg on aarch64 just for diversity
of coverage.)

This will let us make the switch for s390x and aarch64 hosts from
the ad-hoc CI to gitlab.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Thomas Huth <thuth@redhat.com>
Message-id: 20210913101948.12600-1-peter.maydell@linaro.org