New Greeter breaks startup of Terminal by setting invalid values for some LC_* variables

Originally created by @intrigeri on #12079 (Redmine)

./features/scripts/vm-execute localectl                     
Return status: 0
STDOUT:
   System Locale: LC_NUMERIC=US.UTF-8
                  LC_TIME=US.UTF-8
                  LC_MONETARY=US.UTF-8
                  LC_PAPER=US.UTF-8
                  LC_MEASUREMENT=US.UTF-8
       VC Keymap: n/a
      X11 Layout: us
       X11 Model: pc105

These should be en_US.UTF-8 instead of US.UTF-8. This breaks numerous parts of feature/stretch now that I’ve merged the new Greeter in.

Blueprint: https://tails.boum.org/blueprint/greeter_revamp_UI/design_rationale_phase1/formats/

Feature Branch: greeter:bugfix/12079-formats

Attachments

• formats.png
• Greeter.Formats.png
• formats-implemented-greeter-fr-jp.png
• formats-implemented-greeter-fr-us.png
• formats-implemented-session-fr-jp.png
• formats-implemented-session-fr-us.png
• formats-nodate-session-fr-jp.png
• formats-nodate-greeter-fr-jp.png
• formats-nodate-session-fr-us.png
• formats-nodate-greeter-fr-us.png
• formats-language-greeter-en-gb-us.png
• formats-language-greeter-en-gb-us-popoverok.png
• formats-language-session-en-gb.png
• formats-language-session-en-gb-us.png
• formats-language-greeter-en-gb.png
• formats-remove-session-fr-us.png
• formats-remove-greeter-fr-us.png
• French in the USA.png
• French in Japan.png
• GNOME all at once.png
• GNOME restart.png

Parent Task: #8230 (closed)