No backend languages available except English in composerized installations
The folder for localization files was moved in Composer-based installations in 9.5. This change was, however, not reflected in the code that renders the language selector for the backend user settings module.
[BUGFIX] Only English shown as BE language in Composer mode
Using the legacy path for the l10n files folder does not work anymore in
Composer mode, as the folder was moved into `var/` there.
Tested-by: TYPO3com <firstname.lastname@example.org>
Reviewed-by: Georg Ringer <email@example.com>
Tested-by: Georg Ringer <firstname.lastname@example.org>