Reconnect graphical lines properly

[DeniseSl22]

When changing from an interaction to a Graphical line, the arrowhead is not connected to the DataNode again (it is located in the middle of the Node).

[khanspers]

An update: The graphical line is actually connected, but the end of the graphical line ends up in the middle of the node somehow (even though there is no anchor there). So it is necessary to reconnect the graphical line to the appropriate node/label anchor. Here are two screenshots explaining:

Before (regular interaction):

After (converted to graphical line):