update doc and use P2P=LOC for brittle grpo test (#2649)

* update doc and skip brittle grpo test

* fix the path to run the multigpu tests

* increase timeout, use LOC instead of NVL

* typo

* use hf cache from s3 backed cloudfront

* mark grpo as flaky test dues to vllm start

codecov.yml

@@ -19,7 +19,7 @@ coverage:
         if_no_uploads: error
         if_not_found: success
         if_ci_failed: error
-        only_pulls: false
+        only_pulls: true
         flags: null
         paths: null
     patch: