changes the marker ID if it was part of the djs-visual instead of creating a new one.
Adds a random string to the copied marker ID. This ensures we do not have overlaps if the same connection is present multiple times in a preview. While this should not happen, it did happen in the past so better be safe here.
Ensures we copy connections only once in move preview
This PR:
djs-visualinstead of creating a new one.related to https://github.com/bpmn-io/bpmn-js/issues/2179