remove Codex PR Review action

This action stopped working many weeks back, with the error

    ERROR: Quota exceeded. Check your plan and billing details.

Even though I have updated the API key.  Best to just remove it for now,
since the failure is unwelcoming for contributors.

Author: rolandwalker

.github/workflows/codex-review.yml

@@ -4,6 +4,7 @@ Upcoming (TBD)
 Internal
 --------
 * Add test coverage for `client_commands.py`.
+* Remove Codex PR Review action, which stopped working.
 
 
 1.74.1 (2026/06/18)