[web] fix leave channel modal for long thread names
Summary:
This fixes a bug where the modal would gorw really wide if the thread name has a really long name. This diff fixes this bug
Linear task: https://linear.app/comm/issue/ENG-8438/leave-channel-modal-on-web-grows-when-a-thread-has-a-really-long-name
Test Plan:
Please see the screenshots
Before:
After:
Reviewers: inka, ashoat
Reviewed By: ashoat
Subscribers: ashoat, tomek
Differential Revision: https://phab.comm.dev/D12582