[DO NOT MERGE] archive(8.1) exclude: remove versions 8.1 and 3.9.0, part 2: chonky boi

[pepopowitz]

This PR contains a ton of removed files! Viewing "Files changed" will crash your browser.

It targets the branch from #3769, since that one should merge first.

BLOCKED

• archive(8.1) exclude: remove versions 8.1 and 3.9.0, part 1: reviewable steps #3769 should be merged first.

Description

Part of #3731.

Deletes the 8.1/3.9.0 content from the docs. This is the final step in archiving this unsupported version.

Since it's hard to view in the browser, these are the commands I ran for this PR:

rm -rf ./versioned_docs/version-8.1/
rm ./versioned_sidebars/version-8.1-sidebars.json
rm -rf ./optimize_versioned_docs/version-3.9.0/
rm ./optimize_versioned_sidebars/version-3.9.0-sidebars.json

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)
• There is no urgency with this change and can be released at any time.
• In the next couple days, preferably, so I can complete this archival work.

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 Engineerring DRI or delegate.
• My changes require a technical writer review, and I've assigned @christinaausley as a reviewer.

• My changes require a docs infrastructure review.

[akeller]

Hand wavy review because that's all I can do (can barely type TBH)

The base branch was changed.

[pepopowitz]

Sorry to do this @akeller but could I get another approval on this? I merged the other related PR, resulting in this one changing targets to main (as expected)...and it dismissed your approval.

For what it's worth, if approving through the UI is completely unbearable due to the massive quantity of changes, the GitHub CLI provides a method for reviewing/approving from your terminal: https://cli.github.com/manual/gh_pr_review

[pepopowitz]

Merging in a red state -- this is as green as it's going to get, because the massive quantity of changes breaks the two failing checks.