test(interoperability): increase waitForElementByCss timeout for cross-router navigations (#91918)
### What?
Increase the `waitForElementByCss` timeout from the default (~10 s) to
30 s on every cross-router navigation assertion in
`test/e2e/app-dir/interoperability-with-pages/navigation.test.ts`.
### Why?
[Datadog test
runs](https://app.datadoghq.com/ci/test/runs?query=test_level%3Atest%20%40test.source.file%3Atest%2Fe2e%2Fapp-dir%2Finteroperability-with-pages%2Fnavigation.test.ts%20%40test.status%3Afail%20%40test.name%3A%22navigation%20between%20pages%20and%20app%20dir%20It%20should%20be%20able%20to%20navigate%20pages%20-%3E%20app%20and%20go%20back%20an%20forward%22&agg_m=count&agg_m_source=base&agg_t=count&cols=%40test.status%2Ctimestamp%2C%40duration%2C%40test.type%2C%40test.is_known_flaky%2C%40test.name¤tTab=overview&eventStack=&fromUser=false&index=citest&start=1773951834834&end=1774556634834&paused=false)
Navigating between the App Router and Pages Router (in either direction)
always triggers a **full-page reload** because the two routers cannot
share a client-side navigation. In dev mode, the destination page is
compiled on-demand the first time it is visited, which consistently
takes ~13 s in CI.
The default `waitForElementByCss` timeout is ~10 s, so the `app ->
pages` test would intermittently time out before the newly compiled page
finished loading — a classic flaky-test failure that is load-sensitive
and non-deterministic across machines.
This is a test-only fix; no framework behaviour changes.
### How?
Pass `{ timeout: 30000 }` as the second argument to every
`waitForElementByCss` call that waits for an element after a
cross-router navigation (8 call-sites across 4 tests). A comment is
added before each group of calls explaining why the higher value is
necessary.
Verified locally with 3 consecutive runs — all 4 tests pass, and the
previously flaky `app -> pages` case now completes in ~13 s without
timing out.
Co-authored-by: Tobias Koppers <sokra@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>