When destroying an object, destroy its Herald transcripts too
Summary: Ref T5915. Make bin/remove destroy a bit more thorough, since Herald transcripts can have field information in them.
Test Plan: Used bin/remove destroy to nuke revisions, saw their transcripts vanish too.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T5915
Differential Revision: https://secure.phabricator.com/D10306