Show "Corrupt installation" instead of compliance on invalid VERSION file

If a VERSION file exists then Kleopatra requires a valid signature for
this file. If the file is valid then Kleopatra shows the information
read from this file in status bar and About dialog. Additionally, the
compliance status is shown in the status bar if de-vs compliance is
configured. If the signature of the VERSION file couldn't be verified
then Kleopatra shows the hint "Corrupt installation" in the status bar.

(cherry picked from commit ec2c99cc06920a5db35c927ee09531f9eb5dd2af)

• GnuPG-bug-id: T8245