(stable) Fix issue with "Publish/Notify" handling in repositories

Summary:
Fixes T8728. As far as I can tell, I simply got this wrong in D11826. This is not the proper name for the preference.

That change primarily focused on the "spammy junk during import" issue, and the code did get the importing flag right. It looks like my testing in D11827 focused on "during import" and just missed this case.

Test Plan: Grepped for disable-herald. Grepped for herald-disable.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T8728

Differential Revision: https://secure.phabricator.com/D14181