revert: restore behavior before filesystem helper gating (#780)

[sami-marreed]

Bug fix

Related Issue: None.
Reverts #780.

Summary

Revert commit 934d5d8 in full to restore the behavior before filesystem helper gating.

• Restore the previous filesystem-helper prompt guidance and retain the original few-shot conversations.
• Restore the previous shell configuration and split-execution descriptions.
• Remove the two test modules added specifically for the reverted gating behavior.

This is an exact rollback, not evidence that #780 caused the WatsonX CI failures. It also restores the earlier behavior that can advertise filesystem helpers when they are unavailable.

Testing

• Core and CugaLite test suites: 667 passed, 3 skipped (AppWorld corpus is not vendored).
• Tests ran with Evolve disabled and a placeholder OpenAI key for mocked-client construction. The initial focused run was interrupted after stalling.
• Ruff format: 226 files unchanged; Ruff check passed.
• Commit hooks passed.
• Verified the resulting tree matches the parent of fix(cuga-lite): stop advertising filesystem helpers the executor never injects #780 exactly.
• Live WatsonX CI validation pending.

[coderabbitai]

Navigate logical layers of code changes, visualize relationships, and explore their blast radius.

Note

Currently processing new changes in this PR. This may take a few minutes, please wait...

⚙️ Run configuration

Configuration used: Repository: cuga-project/cuga-agent/.coderabbit.yaml

Review profile: CHILL

Plan: Essentials

Run ID: 756e949b-8704-45fd-8d85-70604440f63f

📥 Commits

Reviewing files that changed from the base of the PR and between 934d5d8 and 218f702.

📒 Files selected for processing (6)

• src/cuga/backend/cuga_graph/nodes/cuga_agent_core/policy/execution_policy.py
• src/cuga/backend/cuga_graph/nodes/cuga_lite/adapter/prepare_node.py
• src/cuga/backend/cuga_graph/nodes/cuga_lite/prompt_utils.py
• src/cuga/backend/cuga_graph/nodes/cuga_lite/prompts/mcp_prompt.jinja2
• src/cuga/backend/cuga_graph/nodes/cuga_lite/tests/test_filesystem_helper_gating.py
• src/cuga/backend/cuga_graph/nodes/cuga_lite/tests/test_prepare_node_runtime_gating.py

 _________________________________________________________
< Finding bugs faster than a kid with a magnifying glass. >
 ---------------------------------------------------------
  \
   \   (\__/)
       (•ㅅ•)
       / 　 づ

✨ Finishing Touches

📝 Generate docstrings

• Commit to this branch
• Create a new PR

🧪 Generate unit tests (beta)

• Commit to this branch
• Create a new PR

---

_{Comment @coderabbitai help to get the list of available commands.}