R1:91ee6b78df3d

Make some confusing/weird Calendar fields not configurable on custom EditEngine forms

Summary:
Ref T11816.

- Host gets weird behavior around defaulting to the viewer.
- Invitees get weird behavior around defaulting to the viewer.
- "All Day" is just sort of weird since start / end date aren't customizable.
- Recurring/Frequency are weird here and don't make much sense.

I can't immediately come up with reasons that any of these are particularly useful/valuable to default. More of them can be made…