Checkmk Werk 10740: Kubernetes: don't crash on invalid roles

ID: 10740 Title: Kubernetes: don't crash on invalid roles Component: Checks & agents Level: 1 Class: Bug fix Version: 1.7.0i1 The kubernetes special agent crashed with the message {{ Invalid value for `rules`, must not be `None`CRIT }} if a role without rules was configured in a cluster. This is fixed.