chore(sidebars): sync sidebars in v8.4/3.12.0

[pepopowitz]

Description

Synchronizes sidebars for v8.4/3.12.0.

There are not many meaningful changes here. This is expected, as structural changes in previous versions of the docs happen far less frequently.

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. I'd like to merge these sidebar sync PRs by the end of this week.
• 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.