[BUGFIX] Let live search use getRecordTitle

Live search uses the label configuration from TCA to get the title of a
record. An existing TODO note already suggests to use the method for
this from BackendUtility. Do this now.

Resolves: #59893
Resolves: #59957
Releases: 6.3, 6.2
Change-Id: Ic4aaabed47922863602e770b588fb8dacd9386de
Reviewed-on: https://review.typo3.org/31197
Reviewed-by: Marcin Sągol
Tested-by: Marcin Sągol
Reviewed-by: Nicole Cordes
Reviewed-by: Anja Leichsenring
Reviewed-by: Helmut Hummel
Tested-by: Nicole Cordes
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn