Revert the global "not imported yet" warning in Diffusion until we have better support

Summary:
Partially reverts D8903. This was hacky to begin with, but completely breaks if the filetree is enabled ($view is not an array).

Just toss it until we have a more structured way to insert it into the document properly. I don't think it's especially important (the Herald warning is way more important).

Test Plan: Multiple users reported that stuff is no longer broken.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D8914