docs: update test3 mentions, add test5 mentions

[leohhhn]

Description

This PR updates the mentions of test3 after its deprecation, and adds text on test5.

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

📢 Thoughts on this report? Let us know!

[Kouteki]

LGTM

[notJoon]

Aproved by core members. so remove review/triage-pending flag