Checkmk Werk 12292: Rules: Fix displaying rule with empty service conditions

ID: 12292 Title: Rules: Fix displaying rule with empty service conditions Component: Setup Level: 1 Class: Bug fix Version: 2.1.0i1 Rules with an empty list of service conditions can not be created with the setup these days because they match no service at all. Previous versions made this possible. Displaying these rules was not possible with previous 2.0.0 and lead to a crash "IndexError (list index out of range)".