Remove deprecated object logger
    
    The object logger methods been deprecated for about two years since release
    4.6.0. The log manager used to moneky-patch additional log methods like
    info(), warning(), and error() into API plugin objects. The methods have
    been replaced by calls to module logger objects in 4.6.0.
    
    Remove monkey-patch logger methods, log manager, and its root logger from
    ipapython.ipa_log_manager.
    
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Thomas Woerner <twoerner@redhat.com>