The bootstrap racer covers sync connects only. The gateway's WebSocket dials
(relay connector, Yuanbao, Buzz) go through ``websockets.connect`` →
``loop.create_connection``, whose ``happy_eyeballs_delay`` defaults to ``None``:
a serial walk that burns the full connect timeout on every blackholed AAAA
record before IPv4 answers — the same stall class #114265 reports, one layer up.
``websockets`` forwards unknown kwargs to ``loop.create_connection``, so each
call site passes ``happy_eyeballs_delay=0.25`` (the RFC 8305 delay anyio and
the sync racer already use). One invariant test per call site captures the
kwargs at a mocked ``websockets.connect``.
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