Various fixes for CI, save_only_model for RL, prevent packing multiprocessing deadlocks (#2661)

* lean mistral ft tests, remove e2e torch 2.4.1 test

* make sure to pass save_only_model for RL

* more tests to make ci leaner, add cleanup to modal ci

* fix module for import in e2e tests

* use mp spawn to prevent deadlocks with packing

* make sure cleanup shell script is executable when cloned out

cicd/cleanup.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+set -e
+
+# cleanup old cache files for datasets processing and intermediate mappings
+find /workspace/data/huggingface-cache/hub/datasets -name "cache-*" -type f -mtime +1 -exec rm {} \;
+find /workspace/data/huggingface-cache/hub/datasets -name "*.lock" -type f -mtime +1 -exec rm {} \;