[BUGFIX] TCAtree must use BackendUtility::getRecordTitle()

If building a tree from records the label of an item must be
generated by using BackendUtility::getRecordTitle to be consistent
with the rest of the backend (e.g. the list module).

Change-Id: I3e362be17dc4ef6ea27958b6e440b9f69ddbad0d
Resolves: #65974
Releases: master, 6.2
Reviewed-on: http://review.typo3.org/38101


Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>