Disable DevelopmentSettingsActivity by default

And if for any reason monkey user is able to enter develop option page,
we show nothing.

And update some test to sdk 26.

Change-Id: I3f985e7fe14bd290db73b8c46dd817591df02015
Fixes: 68707778
Test: robotests

tests/robotests/src/com/android/settings/widget/LoadingViewControllerTest.java

@@ -37,7 +37,7 @@ import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 
 @RunWith(SettingsRobolectricTestRunner.class)
-@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
+@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION_O)
 public class LoadingViewControllerTest {
 
     private Context mContext;