[BUGFIX] Hide empty descriptions in textmedia in page module

In the Page module with textmedia content elements the descriptions
are shown below the thumbnails of linked media. If there is no
description an empty line is now suppressed.

Resolves: #81408
Releases: master, 8.7, 7.6
Change-Id: I9f342908f179550bcf2156328117c464bb8c672f
Reviewed-on: https://review.typo3.org/53092


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Jo Hasenau <info@cybercraft.de>
Tested-by: Jo Hasenau <info@cybercraft.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>