[native] Get rid of React.cloneElement stuff in RegistrationTile

Summary:
At some point I wasn't just rendering header and body side-by-side. I then refactored it, but forgot to consider that pulling these apart just to put them back together later makes no sense.

Depends on D7723

Test Plan: Play around with the registrations screens, similar to the video in the preceding diff

Reviewers: atul, ginsu

Reviewed By: atul

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D7724