archive(8.2) isolation: remove all other versions (chonky boi)

[pepopowitz]

Note that this PR targets unsupported/8.2 and will never make it into main. unsupported/8.2, as of this moment, points to the same commit as main.

This PR will be merged in a red state, because there are too many changes for our CI checks to handle.

It will also crush your browser if you view "Files changed."

Description

Part of #4527.

This PR includes the removal of all non-8.2/3.10.0 versions:

• archiving(8.2): delete version docs/version-8.3
• archiving(8.2): delete version docs/version-8.4
• archiving(8.2): delete version docs/version-8.5
• archiving(8.2): delete version docs/version-8.6
• archiving(8.2): delete version docs/next
• archiving(8.2): delete version optimize/version-3.11.0
• archiving(8.2): delete version optimize/version-3.12.0
• archiving(8.2): delete version optimize/version-3.13.0
• archiving(8.2): delete version optimize/version-3.14.0
• archiving(8.2): delete version optimize/next

When should this change go live?

• This is a bug fix, security concern, or something that needs urgent release support.
• This is already available but undocumented and should be released within a week.
• This on a specific schedule and the assignee will coordinate a release with the DevEx team. (apply hold label or convert to draft PR)
• This is part of a scheduled alpha or minor. (apply alpha or minor label)
• There is no urgency with this change and can be released at any time.

PR Checklist

• My changes are for an already released minor and are in /versioned_docs directory.
• My changes are for the next minor and are in /docs directory (aka /next/).

• My changes require an Engineering review, and I've assigned the Engineering DRI or delegate.

• My changes require a technical writer review, and I've assigned @camunda/tech-writers as a reviewer.

• My changes require a docs infrastructure review.

[akeller]

My new computer actually lets me type a comment on these chonky boi PRs! 🚀 😆

This looks good, as far as I can see. Thank you for including a detailed description of the changes!