[native] Increase expansion button tap target in community side drawer

Summary:
https://linear.app/comm/issue/ENG-3608/increase-expansion-button-tap-target-in-community-side-drawer

In my opinion the button is easy enough to tap without the exapnsion, even on my tiny iPod, but whatever.

Before:

After:

Test Plan: Tap the chevron

Reviewers: kamil, bartek

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D13948