Checkmk Werk 14890: Fix possible error on filtering service level of hosts

ID: 14890 Title: Fix possible error on filtering service level of hosts Component: Multisite Level: 1 Class: Bug fix Version: 2.2.0i1 Using the filter "Host service level" for views with hosts with configured custom attributes could lead to an error message like "Internal error: invalid literal for int() with base 10".