Improve tests for Vue 3 migration

What does this MR do and why?

This MR fixes tests for the Vue 3 migration, and also improves some of the test code while we're touching the files

Resolves:

• #413365 (closed)
• #413367 (closed)
• #413313 (closed)
• #413302 (closed)
• #391047 (closed)
• #413322 (closed)

Screenshots or screen recordings

How to set up and validate locally

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