When a paste's file is deleted, drop it from query results
Summary:
We allow files to be deleted from the web UI, including paste files. When a paste's file is deleted, we currently continue to show it in the paste list and then 400 when it's clicked on.
Instead, remove it from the list. (Note that it may stick around if it's cached.)
Test Plan: Purged general cache, deleted a paste's file, viewed paste list, saw no pastes.
Reviewers: dctrwatson, btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T3265
Differential Revision: https://secure.phabricator.com/D6067