Maven gradle E2E test improvements

What does this MR do and why?

• Fixes a mistake introduced in Run E2E Gradle tests on Docker (!201131 - merged). We should use gradle build instead of gradle publishToMavenLocal when testing the package download scenario.

  • See Fix outdated Gradle command in Maven Package Re... (!206460 - merged)
  • Aside from using gradle build, this MR adds Java source files to the package. Without Java files, gradle build does a shortcut and skips the actual download of the package MR review discussion.

• Implements ideas recommended by the maintainer during the review of Use Docker to run Helm Package Registry E2E tests (!204643 - merged):

  • wrap package downloading in a retry block, using the same 180s limit we use for the CI pipeline
  • stop the container in an ensure block

• GitLab Duo suggestion:

  • When stopping the container, wrap in a rescue block so that errors in stopping the container will not mask earlier errors, which are likely more important for troubleshooting

References

• Issue: Investigate & Fix/Quarantine test file: /browse... (#550594 - closed)
• Related MRs:
  • Use Docker to run Helm Package Registry E2E tests (!204643 - merged)
  • Run E2E Gradle tests on Docker (!201131 - merged)
  • Fix outdated Gradle command in Maven Package Re... (!206460 - merged)

Screenshots or screen recordings

NA

How to set up and validate locally

Run the E2E tests locally against GDK, e.g. from within the qa directory, run WEBDRIVER_HEADLESS=false GITLAB_QA_ADMIN_ACCESS_TOKEN='<root-pat>' GITLAB_USERNAME='root' QA_LOG_LEVEL=DEBUG QA_GITLAB_URL=http://gdk.test:3000 bundle exec rspec qa/specs/features/browser_ui/5_package/package_registry/maven_gradle_repository_spec.rb

MR acceptance checklist

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

Related to #550594 (closed)