Update maven repository QA spec

🍋 Context

The Maven repository QA spec runs examples using the some authentication token type: personal access token.

#340869 (closed) has been opened to run them through the other token types:

• CI job token
• deploy token

🔬 What does this MR do and why?

• Use a table based spec to run the same examples through different token types.
• Took this opportunity to cleanup a bit the spec:
  • Use the existing shared context which declares common vars and before / after callbacks.
  • Use private functions to avoid code duplication

🖼 Screenshots or screen recordings

n / a

⚙ How to set up and validate locally

1. Follow https://about.gitlab.com/handbook/engineering/development/ops/package/quality/#how-to-run-them-locally
2. Run the maven scenario:

   WEBDRIVER_HEADLESS=false bundle exec bin/qa Test::Instance::All http://172.16.123.1:8000 -- qa/specs/features/browser_ui/5_package/package_registry/maven_repository_spec.rb --tag orchestrated --tag packages

🏁 MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.