Remove bottom margin from embedded remarkup images

Summary:
{T15473} created a very small but annoying regression. Every embedded images has now an margin at the bottom:

{F718091}

I don't think this is intentional. If you click on the margin the image itself is opened not the lightbox. This revision removes the margin.

Test Plan: Look at tasks with embedded images and see if there is still an margin.

Reviewers: O1 Blessed Committers, valerio.bozzolan, aklapper

Reviewed By: O1 Blessed Committers, valerio.bozzolan, aklapper

Subscribers: aklapper, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25522