[CLEANUP] Remove 'defaultMod' module configuration

This is dead code and can safely be removed.

Resolves: #63653
Releases: master
Change-Id: I90112c8483670a21351cab78b7aca29c64a2a1a1
Reviewed-on: http://review.typo3.org/35149
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Alexander Opitz <opitz.alexander@googlemail.com>
Tested-by: Alexander Opitz <opitz.alexander@googlemail.com>