Historically files to be formatted were added to a listing (via matchers)
to be included in formatting. Instead, this change begins efforts to
instead include all files in format enforcement, relying instead on an
opt out methodology.
PR Close#36940
With this change, we no longer depend on CircleCI to trigger the webhook
(which it sometimes does with considerable delay or not at all).
This has the added benefit that other jobs will not unnecessarily
trigger webhooks and spam the preview server logs. It is only the
`aio_preview` job's webhook that we care about.
Related to #27352.
PR Close#27458