The dual-stack discovery change made the default-local /browser connect
path call discover_local_cdp_url instead of is_browser_debug_ready, so
the old is_browser_debug_ready patch no longer short-circuited the
probe. On the CI runner nothing listens on 9222, so the test fell
through to a REAL chromium launch (which dies headless:
'The platform failed to initialize') and no context note was queued.
Patch the new discovery helper at the mixin's import site instead.
4c96172d9b