Tracker: Tell pose view on Desktop to update its colors and replicant colors

... on B_RESTORE_BACKGROUND_IMAGE (which sets the Desktop color or wallpaper).

Remove kRestoreBackgroundImage, preferring the B_ version we got from
Backgrounds (and represents the same constant). Tracker already imported
this constant long ago.

Fixes #20028.

Change-Id: I6c59f4ddd1b2a7ec0d5e90fe6a8a9671dc66d50e
Reviewed-on: https://review.haiku-os.org/c/haiku/+/10729
Reviewed-by: waddlesplash <[email protected]>
Tested-by: Commit checker robot <[email protected]>

src/kits/tracker/PoseView.cpp

@@ -2240,11 +2240,6 @@ BPoseView::MessageReceived(BMessage* message)
 			AddPosesCompleted();
 			break;
 
-		case kRestoreBackgroundImage:
-			if (ContainerWindow() != NULL)
-				ContainerWindow()->MessageReceived(message);
-			break;
-
 		case B_META_MIME_CHANGED:
 			NoticeMetaMimeChanged(message);
 			break;