Checkmk Werk 12303: Fix cache miss on discovery

ID: 12303 Title: Fix cache miss on discovery Component: Checks & agents Level: 1 Class: Bug fix Version: 2.1.0i1 This fixes a problem with the cache invalidation of the discovery data. This could have two consequences: a performance problem where the hosts would be unnecessarily queries; or the opposite where the data would not be refreshed.