[TASK] Move DatabaseL10nModeUpdate to a row updater

The new DatabaseL10nModeUpdate install tool upgrade wizard that
migrates row content for old "mergeIfNotBlank" fields is now
implemented as the first consumer of the new row updater upgrade
wizard.

Change-Id: If7495ef09e06c5fd611fe95feff640c67d3a672b
Resolves: #79281
Related: #79243
Related: #79279
Releases: master
Reviewed-on: https://review.typo3.org/51277


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>