Harden Avenger against transient Claude harness failure exhaustion (#53043)

Author: Copilot

.github/workflows/avenger.lock.yml

@@ -15,6 +15,7 @@ permissions:
   pull-requests: read
 env:
   GOTOOLCHAIN: auto
+  GH_AW_HARNESS_MAX_RETRIES: "4"
 tracker-id: avenger-ci
 max-turns: 50
 model: claude-haiku-4-5