Protected packages: Apply recommended matchers from testing library

What does this MR do and why?

test: Apply recommended matchers from testing library

MR includes:

• Improving accessibility of the package protection rule table
• Using recommened testing library method findByRole to find elements in VueWrapper

🛠 with ❤ at Siemens

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

MR Checklist (@gerardo-navarro)

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the javascript style guides
• Conforms to the database guides

Screenshots or screen recordings

With this MR, we add the property aria-label to the table. This improves the accessibility of the new setting block

Before	After

How to set up and validate locally

1. Execute adjusted test

yarn jest spec/frontend/packages_and_registries/settings/project/settings/components/packages_protection_rules_spec.js

Related to #413641