fix(cdk/drag-drop): add conditional to scroll update (#23337)

Author: andrewseguin

src/cdk/drag-drop/drag-ref.ts

@@ -1398,7 +1398,8 @@ export class DragRef<T = any> {
 
       // ClientRect dimensions are based on the scroll position of the page and its parent
       // node so we have to update the cached boundary ClientRect if the user has scrolled.
-      if (this._boundaryRect && target.contains(this._boundaryElement)) {
+      if (this._boundaryRect && target !== this._boundaryElement &&
+          target.contains(this._boundaryElement)) {
         adjustClientRect(this._boundaryRect, scrollDifference.top, scrollDifference.left);
       }