ENG-8408 Move datetime field to date field in people attributes

[[id:98e0f14f-78e7-4740-b200-f0096029150c][Testing]]

- The actual act of updating the field and generating the migration took all of

10 minutes. But then I had to update some tests and apply the migration to my

tests database. Because we use three PostgreSQL extensions, I then had to re-apply

those extensions to the test database. Then, finally I got the result back

that I didn't break anything. Hooray :sad: