Increase severity of bin/remove destroy warning

Summary:
Make sure we're 100% clear that this is really, truly not recommended.

Also improve the text itself, and show the objects which are being destroyed more clearly.

Test Plan: Removed objects with bin/remove destroy.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D12952