archive(1.3) isolation: remove all other versions (chonky boi)

[pepopowitz]

Note that this PR targets unsupported/1.3 and will never make it into main. Prior to opening this PR, I reset the unsupported/1.3 branch to the parent of #4475.

It will also be merged in a red state, because it requires follow-up steps to fix the build.

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

Description

Part of #2189.

This is a redo of #2480. The unsupported/1.3 branch has sat dormant for a year and a half. I tried to cherry-pick newer commits in #4474, but I realized there were significantly more PRs to pick than I originally thought, and I decided to blow up the unsupported/1.3 branch and start over.

Included

• archiving(1.3): delete version docs/version-8.2
• archiving(1.3): delete version docs/version-8.3
• archiving(1.3): delete version docs/version-8.4
• archiving(1.3): delete version docs/version-8.5
• archiving(1.3): delete version docs/version-8.6
• archiving(1.3): delete version docs/next
• archiving(1.3): delete version optimize/version-3.10.0
• archiving(1.3): delete version optimize/version-3.11.0
• archiving(1.3): delete version optimize/version-3.12.0
• archiving(1.3): delete version optimize/version-3.13.0
• archiving(1.3): delete version optimize/version-3.14.0
• archiving(1.3): 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]

Merging to a branch that isn't main ✅
Spot checked commits and it looks like we want it!