Document test_stage_unstable_flag consumer as post-run POST_FAILURE

Update global.yml comment to match ci-framework-jobs check-test-unstable-post
instead of run-phase fail plus failure-message.

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

Author: tusharjadhav3302

configs/global.yml

@@ -33,9 +33,9 @@ report_dir: "{{ artifacts_dir }}/test_results"
 # Sets the Ansible Controller Node machine's HOME environment variable
 controller_home_dir: "{{ lookup('ansible.builtin.env', 'HOME') }}"
 # The resources_file and stage_unstable flags are on the Ansible control node's HOME.
-# test_stage_unstable_flag is written only by testing-stage rescues. The ci-framework
-# shiftstack role fails the Zuul job when this file is present in rsynced artifacts;
-# pair with failure-message: unstable on monolithic shiftstack Zuul jobs for yellow UI.
+# test_stage_unstable_flag is written only by testing-stage rescues. The ci-framework-jobs
+# post-run playbook check-test-unstable-post.yaml fails Zuul POST_FAILURE when this file
+# is present in rsynced shiftstack artifacts (run phase stays SUCCESS).
 # stage_unstable_flag is used by soft verification/install workarounds (no end-of-run fail).
 resources_file: "{{ controller_home_dir }}/artifacts/resources.yml"
 stage_unstable_flag: "{{ controller_home_dir }}/artifacts/stage_unstable_flag"