chore: isolation of version 0.26, part 1: remove all other versions

[pepopowitz]

Note that this PR will never make it into main! It is for the unsupported/0.26 branch only.

Also, trying to view the Files changed tab will crush your browser.

Description

Part of #2184.

This is the chonky boi PR for isolating version 0.26, in which we remove all other versions from this unsupported/0.26 branch.

We will merge this PR in a red state, as it requires follow-up work to fix the build, which I intend to put in a separate follow-up PR.

Removes:

• main docs version 1.0
• main docs version 1.1
• main docs version 1.2
• main docs version 1.3
• main docs version 8.0
• main docs version 8.1
• main docs version 8.2
• main docs version next
• optimize version 3.7.0
• optimize version 3.8.0
• optimize version 3.9.0
• optimize version 3.10.0
• optimize version next

When should this change go live?

• This change is not yet live and should not be merged until {ADD_DATE} (apply hold label or convert to draft PR)?
• There is no urgency with this change.
• This change or page is part of a marketing blog, conference talk, or something else on a schedule.
• This functionality is already available but undocumented.
• This is a bug fix or security concern.

PR Checklist

• I have added changes to the relevant /versioned_docs directory, or they are not for an already released version.
• I have added changes to the main /docs directory (aka /next/), or they are not for future versions.
• My changes require an Engineering review, and I've assigned an engineering manager or tech lead as a reviewer, or my changes do not require an Engineering review.
• My changes require a technical writer review, and I've assigned @christinaausley as a reviewer, or my changes do not require a technical writer review.

[akeller]

The diff you're trying to view is too large. We only load the first 3000 changed files.