Test: Fix E2E import/export tests for WP 6.2 compatibility

[priethor]

What

Follow-up to #345 to fix E2E test failures on WordPress 6.2.

Why

The import/export E2E tests were failing on WP 6.2 due to Playwright strict-mode violations. The locator used matched two elements on WP 6.2 (which displays an additional core warning notice), but only one element on newer WordPress versions.

How

Using .filter({ hasText: ... }) to target the specific SCF warning notice by its expected text content rather than relying on element order. This approach is more robust because it explicitly targets the notice we care about, regardless of how many notices are present on the page.

Testing Instructions

1. Run the affected tests against WP 6.2:
   • Create .wp-env.override.json with {"core": "WordPress/WordPress#6.2"}
   • Run npm run wp-env start
   • Run tests: npm run test:e2e tests/e2e/import-export.spec.ts
2. Verify tests also pass on default WP version

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props priethor.

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 33.97%. Comparing base (1e1f998) to head (4cb2ec6).
⚠️ Report is 1 commits behind head on trunk.

Additional details and impacted files

@@             Coverage Diff              @@
##              trunk     #348      +/-   ##
============================================
- Coverage     34.07%   33.97%   -0.11%     
  Complexity     4410     4410              
============================================
  Files           291      291              
  Lines         36914    36914              
============================================
- Hits          12578    12541      -37     
- Misses        24336    24373      +37     

Flag	Coverage Δ
e2e	44.17% <ø> (-0.44%)	⬇️
javascript	15.07% <ø> (ø)
phpunit	29.97% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.