[BUGFIX] Do not sort tree nodes after each append

Nodes should not be sorted after each element append but only once at
the end.

This will reduce the execution time of 
DatabaseTreeDataProvider::buildRepresentationForNode() a lot e.g. when
a category menu tree is generated.

Resolves: #81039
Releases: master, 8.7
Change-Id: I9cb57630f0179a0b2b3c921ca1eb97e7455ce962
Reviewed-on: https://review.typo3.org/52631


Reviewed-by: Sascha Egerer <sascha@sascha-egerer.de>
Tested-by: Sascha Egerer <sascha@sascha-egerer.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christer V <cvi@systime.dk>
Tested-by: Christer V <cvi@systime.dk>
Reviewed-by: Anders Kostending <aha@systime.dk>
Reviewed-by: Jan Helke <typo3@helke.de>
Tested-by: Jan Helke <typo3@helke.de>