[TASK] Drop TYPO3_CONF_VARS['SYS]['contentTable']

There is a config to define the used "contentTable" which is set
by cms extension to tt_content. Using tt_content is hardcoded at
many places and probably no one ever set this option to something
different than "tt_content". The option is dropped now.

Resolves: #60570
Releases: 6.3
Change-Id: I039e7f5c9e0562c54ce671dc7e7a2ac807f8076e
Reviewed-on: http://review.typo3.org/31831


Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Sascha Egerer <sascha@sascha-egerer.de>
Tested-by: Sascha Egerer <sascha@sascha-egerer.de>
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Tested-by: Helmut Hummel <helmut.hummel@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>