REST API: Add tests for global styles endpoint integer ID type

[himanshupathak95]

Trac ticket: https://core.trac.wordpress.org/ticket/61911

This PR adds unit tests for the global styles endpoint ID type fix.

The tests verify that:

1. The endpoint correctly treats IDs as integers
2. The schema properly defines the ID as an integer type
3. The route is registered with the correct ID type and without unnecessary sanitization
4. Updates QUnit fixtures to reflect the endpoint changes

Follow-up of PR #7234.

[github-actions[bot]]

Test using WordPress Playground

The changes in this pull request can previewed and tested using a WordPress Playground instance.

WordPress Playground is an experimental project that creates a full WordPress instance entirely within the browser.

Some things to be aware of

• The Plugin and Theme Directories cannot be accessed within Playground.
• All changes will be lost when closing a tab with a Playground instance.
• All changes will be lost when refreshing the page.
• A fresh instance is created each time the link below is clicked.
• Every time this pull request is updated, a new ZIP file containing all changes is created. If changes are not reflected in the Playground instance, it's possible that the most recent build failed, or has not completed. Check the list of workflow runs to be sure.

For more details about these limitations and more, check out the Limitations page in the WordPress Playground documentation.

Test this pull request with WordPress Playground.

[github-actions[bot]]

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 abcd95, johnbillion.

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

[himanshupathak95]

Hi @johnbillion. I have added the unit tests and updated the existing test files. Now, all the tests are passing. Let me know if the changes look good to you. 🙌🏻

[github-actions[bot]]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 60359 GitHub commit: https://github.com/WordPress/wordpress-develop/commit/5d5235f0001420bebb4ea9e58755c7d526629aa4

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.