Fix Menu tests skip'd in the Popover => Popover2 transition

[cmslewis]

I it.skip'd the following tests during the 2.0 transition promoting Popover2 to the core popover component. Need to get them working again and re-enable them:

// menuTests.tsx
- "children will continue displaying in the same direction if possible"
- "children will flip direction after no more room in the existing direction"

Note: anecdotally, the functionality above does still work in practice; it's just the tests that are failing.