[TASK] Cleanup and deprecate TYPO3_DB occurrences

All instances of $GLOBALS[TYPO3_DB] in the TYPO3 Core classes
except for certain highly used functionalities have been removed.

The places where the TYPO3 Core is expected to have subclasses
within extensions have been marked for deprecation.

Resolves: #78224
Releases: master
Change-Id: Ie65878264679b93940ac9fb86c4758576d98c550
Reviewed-on: https://review.typo3.org/49824


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>