Fixes css class name added to connection to use node id instead of node name

[ajainarayanan]

Problem

• We switched to using node id for a plugin in DOM while rendering nodes and connections
• But we missed out on replacing node id in css classes being applied to connections.
• This caused problems in corner cases where the stage names had spaces and css class based names, eg: table.
• This plugin name with spaces and common names like table in class in the DOM node caused browser to render additional styles that we define under table css class which causes unnecessary deformation in connections.

Fix

• Fix css class for connections to use node id instead of node name.

[gitpod-io[bot]]