Unflake router events deploy test (#91589)
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After upgrading Playwright in #91250 (which brought some performance
improvements), some tests are now exposed to be missing retries around
assertions. `test/e2e/basepath/router-events.test.ts` is one of those
tests, and this PR adds a `retry` around the event log assertion. We're
also replacing the deprecated `check` utility with `retry` when waiting
for the router to be ready.
