R1:0dd6c3653edf

Clean up Blog Post crumbs

Summary: Show the J monogram when internally linked, but nothing externally (cleaner UI). Ref T9360

Test Plan: View post live and internal.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T9360

Differential Revision: https://secure.phabricator.com/D16245