[TASK] Remove EXT/extListArray from DefaultConfiguration

extListArray is obsolete and can be removed. It is already taken
core off in the install tool upgrade process.

Change-Id: Ie9b86f28deebd3aab1031a725d72d852374e5607
Resolves: #56552
Releases: 6.2
Reviewed-on: https://review.typo3.org/28054
Reviewed-by: Anja Leichsenring
Tested-by: Anja Leichsenring
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters