Checkmk Werk 8877: Historic metrics painter: Prevent empty views, improve error handling

ID: 8877 Title: Historic metrics painter: Prevent empty views, improve error handling Component: Multisite Level: 1 Class: Bug fix Version: 1.7.0i1 When adding the "historic metrics painter" to a view, this could result in empty views when none of the fetched row could satisfy the required metrics. Instead of filtering out all rows, we now leave the rows untouched and show an error message in the historic metrics painter.