Werk #14541: Main dashboard: Render host & service problems graphs in certain multi-site setups

In certain multi-site setups, the host and service problems graphs in the main dashboard ("Total host problems", "Total service problems", "Percentage of total service problems") are not rendered. This happens if there are too many Checkmk hosts (hosts running Checkmk sites) in the monitoring, which leads to error messages such as

Sorry, you cannot create combined graphs for more than 100 objects

or

As soon as you add your Checkmk server(s) to the monitoring, a graph showing the history of your
host problems will appear here.

This werk solves this issue for setups with many Checkmk hosts whose sites are however not connected via distributed monitoring to the site(s) on which these hosts are monitored.

To the list of all Werks