Help Drawer - Hide Tours if there are none

`vm.tours` is declared as an empty array (in the controller),
it isn't null, so we need to check the array length.
Otherwise if there are none, the "Tours" title is displayed.

(cherry picked from commit a51f7b29de)

src/Umbraco.Web.UI.Client/src/views/common/drawers/help/help.html

@@ -9,7 +9,7 @@
         <umb-drawer-content>
 
         <!-- Tours -->
-        <div class="umb-help-section" ng-if="vm.tours" data-element="help-tours">
+        <div class="umb-help-section" ng-if="vm.tours.length > 0" data-element="help-tours">
 
             <h5 class="umb-help-section__title">Tours</h5>