Disbale Unsloth's compiled/fast generaton paths for CI

[sreeram-11]

1. Updated test_unsloth_ci.py
   • Avoids Torch Inductor / Unsloth compiled generation issues on ROCm
   • os.environ["UNSLOTH_COMPILE_DISABLE"] = "1"
   • os.environ["UNSLOTH_DISABLE_FAST_GENERATION"] = "1"
2. Removes stale compiled cache before running the CI script (test_unsloth_ci.py)
3. Added a note which tells users that the bitsandbytes library load error message can be ignored. Otherwise, users may assume that the playbook is broken.