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_job.yml

@@ -129,20 +129,7 @@
   status: 5
   started: 1683636528
   stopped: 1683636626
--
-  id: 205
-  run_id: 804
-  repo_id: 6
-  owner_id: 10
-  commit_sha: 6e64b26de7ba966d01d90ecfaf5c7f14ef203e86
-  is_fork_pull_request: 0
-  name: job_2
-  attempt: 1
-  job_id: job_2
-  task_id: 48
-  status: 1
-  started: 1683636528
-  stopped: 1683636626
+
 -
   id: 206
   run_id: 805