Remove unneeded code for filtering latest results
    
    Filtering by system_architecture and system_variant field is done for
    all subject types, not only composes ("productmd.compose.id").
    
    I.e. all latest test results with unique pair of system_architecture and
    system_variant are considered.
    
    Signed-off-by: Lukas Holecek <hluk@email.cz>