[native] Stop gating AppearancePreferences on staffCanSee
Summary: Now that light mode works (it's far from perfect, but it's no longer obviously broken in any way), we can stop gating it on staffCanSee.
Test Plan:
- Log into Release build with non-staff account.
- Make sure Appearance section appears in Profile -> Preferences
- Try changing theme and make sure things continue to work as expected.
Reviewers: tomek, marcin, ginsu, rohan, ashoat
Reviewed By: ashoat
Subscribers: ashoat, abosh
Differential Revision: https://phab.comm.dev/D5621