refactor: Remove block and workspace drag surfaces (#6758)

* refactor: Remove BlockDragSurface.

* refactor: Remove WorkspaceDragSurfaceSvg.

* chore: Remove drag surface-related CSS.

* chore: Removed unused variable in block_dragger.ts.

* chore: Remove references to drag surfaces in comments.

* refactor: Only track icons with visible bubbles for position updates during a drag.

* fix: Remove rendundant condition.

* fix: Remove arg inadvertently reintroduced in merge

core/workspace_dragger.ts

@@ -20,9 +20,6 @@ import type {WorkspaceSvg} from './workspace_svg.js';
 /**
  * Class for a workspace dragger.  It moves the workspace around when it is
  * being dragged by a mouse or touch.
- * Note that the workspace itself manages whether or not it has a drag surface
- * and how to do translations based on that.  This simply passes the right
- * commands based on events.
  *
  * @alias Blockly.WorkspaceDragger
  */
@@ -67,7 +64,6 @@ export class WorkspaceDragger {
     if (common.getSelected()) {
       common.getSelected()!.unselect();
     }
-    this.workspace.setupDragSurface();
   }
 
   /**
@@ -80,7 +76,6 @@ export class WorkspaceDragger {
   endDrag(currentDragDeltaXY: Coordinate) {
     // Make sure everything is up to date.
     this.drag(currentDragDeltaXY);
-    this.workspace.resetDragSurface();
   }
 
   /**