This diff fixes several nits found while doing D16474:
- Use the block hash as hex string in assert_equal. This is a bit slower but the debug.log shows the hash as hex string so it's much easier to debug via combine_logs.py
- Don't override the default timeout, this is uncessary and could introduce spurious failures
- Consistently use make_conform_to_ctor
- Fix a related but wrong comment in messages.py