gitlab: support disabling job auto-run in upstream

In forks QEMU_CI=1 can be used to create a pipeline but not auto-run any
jobs. In upstream jobs always auto-run, which is equiv of QEMU_CI=2.

This supports setting QEMU_CI=1 in upstream, to disable job auto-run.
This can be used to preserve CI minutes if repushing a branch to staging
with a specific fix that only needs testing in limited scenarios.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20230608164018.2520330-6-berrange@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

.gitlab-ci.d/base.yml

@@ -109,6 +109,16 @@ variables:
     - if: '$QEMU_CI != "2" && $CI_PROJECT_NAMESPACE != $QEMU_CI_UPSTREAM'
       when: manual
 
+    # Upstream pipeline jobs start automatically unless told not to
+    # by setting QEMU_CI=1
+    - if: '$QEMU_CI == "1" && $CI_PROJECT_NAMESPACE == $QEMU_CI_UPSTREAM && $CI_COMMIT_BRANCH =~ /staging-[[:digit:]]+\.[[:digit:]]/'
+      when: manual
+      variables:
+        QEMU_CI_CONTAINER_TAG: $CI_COMMIT_REF_SLUG
+
+    - if: '$QEMU_CI == "1" && $CI_PROJECT_NAMESPACE == $QEMU_CI_UPSTREAM'
+      when: manual
+
     # Jobs can run if any jobs they depend on were successful
     - if: '$QEMU_JOB_SKIPPED && $CI_PROJECT_NAMESPACE == $QEMU_CI_UPSTREAM && $CI_COMMIT_BRANCH =~ /staging-[[:digit:]]+\.[[:digit:]]/'
       when: on_success