Fix robotests fail if turning on silky home by default

Bug: 179136903
Test: robotests
Change-Id: Ic620a5061fe7b778076970fd01f212a7aa95bf9e

tests/robotests/src/com/android/settings/backup/BackupSettingsHelperTest.java

@@ -35,8 +35,10 @@ import android.content.res.Resources;
 import android.os.IBinder;
 import android.os.RemoteException;
 import android.os.UserHandle;
+import android.util.FeatureFlagUtils;
 
 import com.android.settings.R;
+import com.android.settings.core.FeatureFlags;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -81,6 +83,7 @@ public class BackupSettingsHelperTest {
         when(mBackupManager.getCurrentTransport()).thenReturn("test_transport");
         mBackupSettingsHelper = new BackupSettingsHelper(mContext);
         mUserManager = Shadow.extract(mContext.getSystemService(Context.USER_SERVICE));
+        FeatureFlagUtils.setEnabled(mContext, FeatureFlags.SILKY_HOME, false);
     }
 
     @Test