Checkmk Werk 15688: Switch agent-receiver certificate

ID: 15688 Title: Switch agent-receiver certificate Component: Checks & agents Level: 1 Class: New feature Version: 2.3.0b1 Previous to this Werk the <tt>agent-receiver</tt> used its own certificate for TLS. Since the CN was identical to the general site certificate the agent-receiver now uses this general certificate. CN and signing CA stay the same, therefore all supported clients continue to work.