[native] fix oversized username container in message header

Summary:
This diff fixes a bug where the username container in the message header was oversized so pressing to the right of it would open up the profile bottom sheet

Linear task: https://linear.app/comm/issue/ENG-6458/pressing-to-the-right-of-username-on-native-opens-profile

Test Plan:
Please see demo video + screenshot below

this is a screenshot of the container now

Reviewers: atul, inka

Reviewed By: atul

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D10982