Remove flaky test for cursor drag from presubmit

These tests run fine in isolation (verified both on a physical Pixel 3
and on a Cuttlefish emulator via acloud), but are flaky in presubmits.

Bug: 159628732
Test: Presubmit
Change-Id: Ia27e05543e2647c42e06a684a3ae5c11c074a5fb

core/tests/coretests/src/android/widget/EditorCursorDragTest.java

@@ -37,7 +37,6 @@ import static org.junit.Assert.assertTrue;
 import android.app.Activity;
 import android.app.Instrumentation;
 import android.graphics.Rect;
-import android.platform.test.annotations.Presubmit;
 import android.text.Layout;
 import android.text.Spannable;
 import android.text.SpannableString;
@@ -96,7 +95,6 @@ public class EditorCursorDragTest {
         mMotionEvents.clear();
     }
 
-    @Presubmit
     @Test
     public void testCursorDrag_horizontal_whenTextViewContentsFitOnScreen() throws Throwable {
         String text = "Hello world!";