Remove redundant translations

Summary:

• Remove some redundant copies of translations after D4985.
• Make some %d more grammatical, "run this command" reads better than "run this 1 command". In context, these numbers are always very small, so counting them even in the >1 variants aren't useful.
• Fix subscriber(s).

Test Plan: Looked at an unsubscribe story, saw translation.

Reviewers: chad

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D4989