[TASK] Load defaultConfigArray just once in AllConfiguration

Currently the method getDefaultConfigArrayComments is
called for every setting but should only be called once.
The method parses the whole defaultconfiguration file so
maybe this does speed up things a little bit.

Resolves: #52555
Releases: 6.2
Change-Id: I65d0151b200a657052691f52211f1e8edaf38019
Reviewed-on: https://review.typo3.org/24419
Reviewed-by: Markus Klein
Tested-by: Markus Klein