Scale bubble bar to the width of the handle

When animating bubble bar from the stash handle, scale the width to the
handle.
Bubble bar is already almost the size of the handle, but a small scale
is still added.

Bug: 345488489
Flag: com.android.wm.shell.enable_bubble_bar
Test: atest TransientBubbleStashControllerTest
Test: slow animations down and unstash and stash bubble bar, observe
  that the width of the bubble bar scales down to the handle
Change-Id: I54dc228fa41d4d494bfb15e191d2ba563c0970c7

quickstep/src/com/android/launcher3/taskbar/bubbles/BubbleStashedHandleViewController.java

@@ -172,6 +172,13 @@ public class BubbleStashedHandleViewController {
         mRegionSamplingHelper = null;
     }
 
+    /**
+     * Returns the width of the stashed handle.
+     */
+    public int getStashedWidth() {
+        return mStashedHandleWidth;
+    }
+
     /**
      * Returns the height of the stashed handle.
      */