trust: always use oddjobd helper for fetching trust information
    
    Since introduction of privilege separation in IPA framework none of the
    operations that require direct access to the framework's credentials can
    be done. All authentication has to be performed with GSSAPI.
    
    As result, we cannot obtain TGT for HTTP/.. principal with kinit
    anymore, so it is better to re-route all types of trust to oddjobd
    helper and get rid of casing out two-way trust.
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1438366
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>