R1:27b78d214790

Don't use handles in the Calendar event name migration

Summary:
Fixes T8209. Using handles can now cause cache fills as a side effect of T7707. Use a raw query instead.

I'll follow up on T8209 with some context and ideas for longer-term fixes.

Test Plan:
- Set event names to `''`.
- Reran migration with `--apply ... --trace`.
- Saw migration work correctly without executing cache fills.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T8209

Differential…