fix(caretaker): clear lock on NEEDS_HUMAN transition (#28601)

tools/caretaker-agent/cloudrun/triage-worker/db/issues_store.py

@@ -74,6 +74,8 @@ class IssuesStore:
             transaction.update(doc_ref, {
                 "status": "NEEDS_HUMAN",
                 "error": "Max triage attempts (2) exceeded due to prior worker crash or timeout",
+                "lock.holder": None,
+                "lock.expires_at": None,
                 "updated_at": firestore.SERVER_TIMESTAMP
             })
             return ClaimAction.NEEDS_HUMAN

tools/caretaker-agent/cloudrun/triage-worker/tests/test_issues_store.py

@@ -53,6 +53,8 @@ class TestIssuesStore(unittest.TestCase):
             args[1]["error"],
             "Max triage attempts (2) exceeded due to prior worker crash or timeout",
         )
+        self.assertIsNone(args[1]["lock.holder"])
+        self.assertIsNone(args[1]["lock.expires_at"])
 
     def test_acquire_lock_active_lock_by_other_holder(self):
         """acquire lock when active lock held by another worker should skip"""