Repair wp/6.4 branch Actions: Fix flaky interactivity router navigate e2e test

[desrosj]

What?

Makes the "should update the HTML only for the latest navigation" test in test/e2e/specs/interactivity/router-navigate.spec.ts wait until the browser has requested both linked pages before letting either request through.

Why?

The test holds each page request in a page.route() handler, and the functions that let a request through (resolveLink1 and resolveLink2) are only assigned once those handlers run. The test only waited for the page's own navigation counter, which can reach 2 before Playwright has run the handlers, so calling resolveLink2() could fail with TypeError: resolveLink2 is not a function. This branch has the same race in its copy of the test, so the fix is included for consistency with the wp/7.1–wp/6.8 stacks.

Upstream

A straight cherry-pick of e693c18 (WordPress#80178) from trunk.

Use of AI Tools

This PR was created by Claude Code under my supervision. All code should be treated as AI-produced and not yet reviewed by a human until this PR is marked Ready for Review.

🤖 Generated with Claude Code

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[desrosj]

Moved to WordPress#83692. The branch is left in place.