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

docs/config.qmd

@@ -505,6 +505,7 @@ save_strategy: # Set to `"no"` to skip checkpoint saves, `"epoch"` at end of eac
 save_steps: # Leave empty to save at each epoch, integer for every N steps. float for fraction of total steps
 saves_per_epoch: # number of times per epoch to save a checkpoint, mutually exclusive with save_steps
 save_total_limit: # Checkpoints saved at a time
+save_only_model: # Save only the model weights, skipping the optimizer. Using this means you can't resume from checkpoints.
 # Maximum number of iterations to train for. It precedes num_epochs which means that
 # if both are set, num_epochs will not be guaranteed.
 # e.g., when 1 epoch is 1000 steps => `num_epochs: 2` and `max_steps: 100` will train for 100 steps