Match 5-character rule codes in ecosystem check
Summary
--
I noticed while extending the regex to match human-readable names that it also didn't cover the
ASYNC rules, which have five letters in the rule code. For example, #24644 revealed no new
diagnostics in the ecosystem, but a local run on my cached ecosystem repos revealed many
diagnostics. This won't show up as a diff in CI on this PR but should help with ecosystem checks on
the ASYNC rules in the future.
