[TASK] Deprecate BE/languageDebug

As feedback from translators: Setting
BE/languageDebug=true clutters the
backend so heavily, that the feature
is of little use nowadays. The patch
deprecates the toggle.

Resolves: #100657
Releases: main
Change-Id: I8283a780375b05630aa7050a8e2415ea1bdbc860
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78727


Tested-by: Josef Glatz <typo3@josefglatz.at>
Reviewed-by: Josef Glatz <typo3@josefglatz.at>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>