Remove combo box used to select which channel information would be displayed

This mechanism was not working correctly when we try to set the combo items based on the label PVs.

99-Shared/llrf/scripts/loadMacroChannelScalling.py

-from org.csstudio.display.builder.runtime.script import PVUtil
-                                                  
-channel = PVUtil.getString(pvs[0]).split(" ")[2]
-                                    
-# Adding the macros on the widget that will consume this script
-widget.getPropertyValue("macros").add("CHANNEL", channel)
-
-widget.setPropertyValue("file", "")
-widget.setPropertyValue("file", "scaling.bob")