[rust-launcher] Remove old Python launcher

[barakeinav1]

Context

Follow-up from PR #2326 (port node launcher to Rust). Tracked in #2598.

Problem

The old Python launcher files still exist in the repo (kept as a safety net during the transition):

• tee_launcher/launcher.py
• tee_launcher/test_launcher.py
• tee_launcher/test_launcher_config.py
• tee_launcher/requirements.txt
• tee_launcher/__init__.py
• tee_launcher/launcher.md
• tee_launcher/user-config.conf

Additionally, flake.nix has a PYTHONPATH reference to ./tee_launcher.

Action

After the Rust launcher is validated in production:

• Delete tee_launcher/ directory
• Remove Python test dependencies
• Clean up flake.nix PYTHONPATH reference
• Remove any CI steps that reference the Python launcher