Ticket 49968 - Confusing CRITICAL message: list_candidates - NULL idl was recieved from filter_candidates_ext
    
    Bug Description:
    	When a filter component is indexed but returns an empty IDL
    	an alarming message is logged although it is normal.
    
    Fix Description:
    	Remove the alarming message
    
    https://pagure.io/389-ds-base/issue/49968
    
    Reviewed by: Mark Reynolds
    
    Platforms tested: F27 + testcase
    
    Flag Day: no
    
    Doc impact: no