Shorten buttons on Leaving High Security Page
Summary: Changes the text to just "Stay", which is still obvious what it means, with less copy. Fixes T7027
Test Plan: Now works on mobile.
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T7027
Differential Revision: https://secure.phabricator.com/D12075