Follow up of T7107: Kleopatra: Option "PublicKeyEncryptionOnly"

Both options "Use symmetric encryption only" and "Use public key encryption only" cause the respective other option to be greyed out in the sign/encrypt dialog, with no hint why.

Please add the tooltip "Symmetric encryption is disabled in the settings." and "Public key encryption is disabled in the settings."

In the first case this tooltip can (and should imho) replace the one already there.
For the second one, I'd place it at the "Encrypt for me" option.