Fix TestActionsCollaborativeOwner (#36657)

In #32562, I incorrectly assigned mismatched `repo_id` values to the
`action_run` and `action_run_job` fixtures used in
`TestActionsCollaborativeOwner`. The changes introduced in #36173 will
cause the test to fail. This PR removes the incorrect fixtures and
switches to using mock workflows to test the relevant functionality.

models/fixtures/action_run.yml

@@ -139,26 +139,7 @@
   updated: 1683636626
   need_approval: 0
   approved_by: 0
--
-  id: 804
-  title: "use a private action"
-  repo_id: 60
-  owner_id: 40
-  workflow_id: "run.yaml"
-  index: 189
-  trigger_user_id: 40
-  ref: "refs/heads/master"
-  commit_sha: "6e64b26de7ba966d01d90ecfaf5c7f14ef203e86"
-  event: "push"
-  trigger_event: "push"
-  is_fork_pull_request: 0
-  status: 1
-  started: 1683636528
-  stopped: 1683636626
-  created: 1683636108
-  updated: 1683636626
-  need_approval: 0
-  approved_by: 0
+
 -
   id: 805
   title: "update actions"