Checkmk Werk 15925: Fix selection while editing downtimes

ID: 15925 Title: Fix selection while editing downtimes Component: Multisite Level: 1 Class: Bug fix Version: 2.3.0b1 If you edited downtimes in a distributed setup, the selection via checkboxes was not processed correctly if downtime IDs were identical on different sites. This resulted in editing all downtimes with the same ID even if e.g. only one downtime was selected for editing.