fix!: re-remove block and workspace drag surfaces (#7070)

* 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.

* chore: fixup parameter from rebase

---------

Co-authored-by: Aaron Dodson <adodson@google.com>

core/scrollbar.ts

@@ -754,11 +754,6 @@ export class Scrollbar {
     // Look up the current translation and record it.
     this.startDragHandle = this.handlePosition;
 
-    // Tell the workspace to setup its drag surface since it is about to move.
-    // onMouseMoveHandle will call onScroll which actually tells the workspace
-    // to move.
-    this.workspace.setupDragSurface();
-
     // Record the current mouse position.
     this.startDragMouse = this.horizontal ? e.clientX : e.clientY;
     this.onMouseUpWrapper_ = browserEvents.conditionalBind(
@@ -793,8 +788,6 @@ export class Scrollbar {
 
   /** Release the scrollbar handle and reset state accordingly. */
   private onMouseUpHandle() {
-    // Tell the workspace to clean up now that the workspace is done moving.
-    this.workspace.resetDragSurface();
     Touch.clearTouchIdentifier();
     this.cleanUp();
   }