Upgrade Redis to 6.0.10

What does this MR do?

This patch upgrades redis from 5.0.9 to 6.0.10. This is a major version upgrade. We are primarily interested in threaded I/O for use on gitlab.com.

That's why this patch also introduces config options for threaded I/O.

Related issues

• https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/12346
• gitlab-com/gl-infra&395 (closed)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion

Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• Pipeline is green on dev.gitlab.org if the change is touching anything besides documentation or internal cookbooks
• trigger-package has a green pipeline running against latest commit

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for the GitLab Chart opened