[BUGFIX] Fix localization of the language module

The table headers are not translatable yet.
Replace them with f:translate tags.

Change-Id: Ibe9fc989eba193f3401f40b1b7f5f8be081189ef
Resolves: #49401
Releases: 6.2, 6.1, 6.0
Reviewed-on: https://review.typo3.org/21671
Reviewed-by: Chris topher
Tested-by: Chris topher
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe