gitlab: remove obsolete job rules for TEMPORARILY_DISABLED variable

We previously had a 'rules:' entry that caused a job to be skipped if
the variable "TEMPORARILY_DISABLED" was set. This is no longer needed
since we can set a similar flag in ci/manifest.yml and re-generate
to temporarily skip a job.

Unfortunately the 'rules:' entry had an unexpected side-effect on
the pipelines that was never previously noticed. Instead of only
running pipelines on push, the mere existance of the 'rules:' entry
caused triggering of pipelines on merge requests too.

The newly auto-generated ci/gitlab.yml file does not have a 'rules:'
for the container job template, and thus only runs on git push.

The result is that build jobs try to run on merge requests and the
container jobs they depend on don't exist. This breaks the entire
pipeline with a message that the config is invalid due to broken
job dependencies.

This fixes a regression introduced in

  commit ccc7a44adbea003d6a0dc2f156adb2856c28bd4c
  Author: Daniel P. Berrangé <berrange@redhat.com>
  Date:   Thu Sep 9 14:49:01 2021 +0100

    ci: re-generate containers/gitlab config from manifest

Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

.gitlab-ci.yml

@@ -18,10 +18,6 @@ include: '/ci/gitlab.yml'
 
 .native_build_job:
   extends: .gitlab_native_build_job
-  rules:
-    - if: "$TEMPORARILY_DISABLED"
-      allow_failure: true
-    - when: on_success
   cache:
     paths:
       - ccache/
@@ -45,10 +41,6 @@ include: '/ci/gitlab.yml'
     paths:
       - ccache/
     key: "$CI_JOB_NAME"
-  rules:
-    - if: "$TEMPORARILY_DISABLED"
-      allow_failure: true
-    - when: on_success
   before_script:
     - *script_variables
   script: