The flag is true by default so the behavior does not change.

Next steps:

Use the flag for updated debugger module names:
  - Frontend server: make the current behavior controlled
    by the flag non-conditional
  - Frontend server: add more debugging names changes under
    the same flag, false by default
  - Dwds: make changes required for the new module names.
  - Flutter tools: when matching dwds changes roll to flutter,
    pass the flag to the frontend server again.

- Cleanup:
  - Frontend server: make new behavior default
  - Flutter tools: remove uses of the flag.
  - Frontend server: remove the flag.

Towards: https://github.com/dart-lang/webdev/issues/1692
Helps: https://github.com/flutter/flutter/issues/106727