Fix some minor curtain overflow/wrap issues

Summary:
Fixes T12503.

• Users with creative usernames like MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM could overflow "Subscribers" in the curtain UI.
• Other content like packages could also overflow.
• Users with interesting and unique names like WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW who were also away or disabled could get a linebreak between their availability dot and their username.

Test Plan:
See T12503 for "before" screenshots. Also tested mobile, which looked fine, but didn't screenshot it.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12503

Differential Revision: https://secure.phabricator.com/D17650