ci: Make test-docs job depend on sanity job

Without this, the test-docs job could end up waiting for manual action
after the sanity job failed, which prevented the pipeline as a whole
from having failed status.

(This means the test-docs job will no longer exist in one corner case
where it did before, when pushing directly to a non-master branch of
the main repository. That should be fine, since the docs are only
deployed from master.)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7676>

.gitlab-ci.yml

@@ -100,18 +100,12 @@ test-docs:
   # Cancel job if a newer commit is pushed to the same branch
   interruptible: true
   stage: deploy
-  needs: []
+  needs:
+    - sanity
   rules:
-    - *ignore_scheduled_pipelines
-    - if: *is-main-master
-      changes: *docs-or-ci
-      when: never
     - if: *is-pre-merge-for-marge
       changes: *docs-or-ci
       when: on_success
-    - if: *is-post-merge-not-for-marge
-      changes: *docs-or-ci
-      when: on_success
     - if: *is-forked-branch-or-pre-merge
       changes: *docs-or-ci
       when: manual