If no keyserver is configured for GnuPG then Kleopatra's configuration dialog shows
i.e. the option "Use OpenPGP keyserver" is erroneously checked and the input field shows the not very user-friendly default value "hkps://none" (as reported by gpgconf) as placeholder text.
Expected:
- The option "Use OpenPGP keyserver" is not checked if no keyserver is configured for GnuPG
- The input field should not show anything
