Fallback code block to automatically parse Java Versions on Arch Linux

What does this MR do and why?

Adds a fallback codeblock to the app.classes.shared.helpers.Helpers.find_java_installs function which supports best-effort java_version array population.

Screenshots or screen recordings

How to set up and validate locally

Any Arch environment should work as normal, but will now have an auto populated Java Override field, I'm using a binhex/arch-crafty-4 container.

MR acceptance checklist

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

• Have you checked this doesn't interfere/conflict/duplicate someone elses work?
• Have you fully tested your changes?
• Have you resolved any lint issues?
• Have you assigned a reviewer?
• Have you applied correct labels?