Add delegate_to localhost for test_stage_unstable_flag cleanup

Match mark_test_stage_unstable.yml so the flag is always removed on the
Ansible control node even if ocp_testing pre_tasks run in a remote context.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: tusharjadhav3302

playbooks/ocp_testing.yaml

@@ -14,6 +14,7 @@
       ansible.builtin.file:
         path: "{{ test_stage_unstable_flag }}"
         state: absent
+      delegate_to: localhost
 
     - name: Update ocp_deployment_topology with overrides if defined
       # Apply ocp_deployment_topology_override on top of the base topology