refactor: Update alt-text-generation e2e selectors to use ARIA roles

[Infinite-Null]

What, Why, and How?

Part of #778

This PR updates the alt-text-generation E2E tests (tests/e2e/specs/experiments/alt-text-generation.spec.js) to follow Playwright's recommended best practices. It replaces brittle CSS selectors and DOM structure-dependent locators with resilient, user-facing locators such as getByRole, getByText, and other accessibility-based queries.

Changes

• Replaced CSS and DOM structure-dependent selectors with Playwright user-facing attributes.

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Sonnet 4.6
Used for: Code review, PR description

Testing Instructions

Verify that CI passes, or run the updated E2E test locally:

npm run test:e2e tests/e2e/specs/experiments/alt-text-generation.spec.js

Changelog Entry

Developer: Updated alt-text-generation E2E selectors to use Playwright user-facing attributes.

[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.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: Infinite-Null <ankitkumarshah@git.wordpress.org>

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 75.50%. Comparing base (9db55ee) to head (91bfcb6).

Additional details and impacted files

@@            Coverage Diff             @@
##             develop     #828   +/-   ##
==========================================
  Coverage      75.50%   75.50%           
  Complexity      2086     2086           
==========================================
  Files             99       99           
  Lines           8626     8626           
==========================================
  Hits            6513     6513           
  Misses          2113     2113           

Flag	Coverage Δ
unit	75.50% <ø> (ø)

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

☔ View full report in Codecov by Harness.
📢 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.