refactor: replace bash-based e2e test runner with Python script

[doitian]

Summary

This PR replaces the bash-based e2e test runner in the GitHub Actions workflow with a comprehensive Python script that provides better error handling, process management, and maintainability.

Changes

New Python E2E Test Runner (tests/bruno/e2e/run_e2e_local.py)

• Comprehensive process management: Properly handles background processes (start.sh, Bruno tests) with signal handlers for graceful shutdown
• Better error handling: Checks prerequisites, validates workflow directories, and provides clear error messages
• Improved cleanup: Ensures all processes (ckb, fnn, bitcoind, lnd) are properly terminated on exit or interrupt
• Real-time output streaming: Streams output from background processes with prefixes for better debugging
• Maintainability: Single Python script that's easier to understand and modify than complex bash scripts

GitHub Actions Workflow Simplification

• Simplified .github/workflows/e2e.yml to call the Python script instead of inline bash commands
• The Python script handles all the complexity (prebuild, starting nodes, waiting for ports, running tests)
• Maintains the same behavior as before but with better structure

Minor Fix

• Reduced retry wait time in tests/nodes/wait.sh from 30 seconds to 10 seconds for faster feedback

Benefits

1. Better maintainability: Python code is easier to read, test, and modify than complex bash scripts
2. Improved error handling: Proper signal handling and cleanup ensures processes don't leak
3. Better debugging: Real-time output streaming with prefixes makes it easier to identify issues
4. Consistency: Same script can be used both locally and in CI

Testing

The script maintains the same behavior as the previous bash-based approach and works with all existing e2e workflows:

• 3-nodes-transfer
• cross-chain-hub
• funding-tx-verification
• udt

[chenyukang]

I'm not sure whether it's better to maintain, after all it's 551 new lines code added and only 18 lines deleted, i prefer to shorter code.