TAPL Increase size of Background to Overview swipe gesture

The instrumentation is using the swipe height, not width, for when in
landscape. Ideally this should be plumbed through but it isn't yet so fix
with a bigger gesture.

Test: TaplTestNexus#testBackground
Bug: 184059820
Change-Id: Id19f65f51468af707baea0a1b31569bb84f7fcb8

tests/tapl/com/android/launcher3/tapl/Background.java

@@ -122,7 +122,9 @@ public class Background extends LauncherInstrumentation.VisibleContainer {
                     endY = startY - swipeLength;
                 } else {
                     startX = getSwipeStartX();
-                    endX = startX - swipeLength;
+                    // TODO(b/184059820) make horizontal swipe use swipe width not height, for the
+                    // moment just double the swipe length.
+                    endX = startX - swipeLength * 2;
                     startY = endY = mLauncher.getDevice().getDisplayHeight() / 2;
                 }