Remove duplicate addition of preferences item

After change I7ec4a0be the "Show Change Number In Changes Table" is
being added to the grid twice.

This does not result in the item being displayed twice.  It is only
displayed once, but has an empty table row above it.

Change-Id: I76cdcdb7931e3a2c8e2eb465f40d2d7abbc91bf8
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyPreferencesScreen.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyPreferencesScreen.java
index af3129b..25c21bf 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyPreferencesScreen.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyPreferencesScreen.java
@@ -133,7 +133,7 @@
     sizeBarInChangeTable = new CheckBox(Util.C.showSizeBarInChangeTable());
     legacycidInChangeTable = new CheckBox(Util.C.showLegacycidInChangeTable());
 
-    final Grid formGrid = new Grid(11, 2);
+    final Grid formGrid = new Grid(10, 2);
 
     int row = 0;
     formGrid.setText(row, labelIdx, "");
@@ -172,10 +172,6 @@
     formGrid.setWidget(row, fieldIdx, legacycidInChangeTable);
     row++;
 
-    formGrid.setText(row, labelIdx, "");
-    formGrid.setWidget(row, fieldIdx, legacycidInChangeTable);
-    row++;
-
     formGrid.setText(row, labelIdx, Util.C.diffViewLabel());
     formGrid.setWidget(row, fieldIdx, diffView);