Translatable unused sentences in Greeter translation

In Transifex I see translation of unused sentences about the Greeter (they are in po/*.po in devel and in “Tails Misc - tails.pot” in Transifex):

-Some have the comment “This string will never be displayed in the 1st version of the greeter.” It seems the second version is not under development, so can you make theses sentences untranslatable?

-others strings don’t have this comment but was not used in the Greeter:
“_Windows Camouflage”, “_Time Zone”, “Failed to relock persistent storage.” and “Relock Persistent Storage”. Can you also make them unstranslatable?

Feature Branch: https://salsa.debian.org/tails-team/tails/merge_requests/39/commits

Related issues

Blocks #16209
Blocked by #16095 (closed)

Original created by @xin on 17058 (Redmine)

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