Checkmk Werk 13041: mtr agent plugin: fix multiple issues

ID: 13041 Title: mtr agent plugin: fix multiple issues Component: Checks & agents Level: 1 Class: Bug fix Version: 2.1.0i1 Multiple issues prohibited running mtr agent plugin with a minimal config: A already running mtr process was not detected correctly. Default Values where not applied correlty, instead a empty string was used for multiple missing values.