doc: update FAQ to mention aqa-tests branches

[sxa]

Based on things seen in:

• https://github.com/adoptium/temurin-build/issues/3685#issuecomment-2075133310
• https://github.com/adoptium/infrastructure/issues/3501#issuecomment-2105675393
• https://github.com/adoptium/aqa-tests/issues/5300#issuecomment-2104830025

Checklist

• [x] commit message has one of the standard prefixes
• [x] faq.md updated if appropriate
• [ ] other documentation is changed or added (if applicable)
• [ ] playbook changes run through VPC or QPC (if you have access)
• [x] VPC/QPC not applicable for this PR
• [ ] for inventory.yml changes, bastillion/nagios/jenkins updated accordingly

[sxa]

Style suggestion (active voice) - could change to:

I have no preference, so I've switched the wording to what you've recommended.