[CLEANUP] Remove leftover bigDoc class+CSS

The different-sized document templates
were deprecated and removed within the
last versions.

However, CSS classes and BigDocumentTemplates
were still found but are not used anymore,
thus they can be removed.

Releases: master
Resolves: #63441
Change-Id: Ia52940138eba39346ca10962cd2de9829809efc2
Reviewed-on: http://review.typo3.org/34801
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>