NBI: disable update check again

 - Hide check-for-updates step from the (windows) installer again
   since it is a no-op with the current NB release model
 - reverts apache#1348 without changing codepaths outside the checkbox
   logic to reduce risks of other side effects
 - can be re-enabled using a property

nbbuild/installer/engine/src/org/netbeans/installer/wizard/components/panels/netbeans/NbPreInstallSummaryPanel.java

@@ -495,7 +495,7 @@ protected void initialize() {
                 removeUserdirCheckbox.doClick();
             }
 
-            if (nbBasePresent) {
+            if (nbBasePresent && Boolean.getBoolean(CHECK_FOR_UPDATES_PROPERTY)) {
                 checkForUpdatesCheckbox.setSelected(true);
                 System.setProperty(CHECK_FOR_UPDATES_CHECKBOX_PROPERTY, Boolean.TRUE.toString());