XWIKI-21631: Tour generates a bottom scroll-bar, when items are created near the margins (#3616)

* Removed a useless class from the popover-navigation
* Overwrote a style from bootstrap-tour with a precise selector

xwiki-platform-core/xwiki-platform-tour/xwiki-platform-tour-ui/src/main/resources/TourCode/TourJS.xml

@@ -214,7 +214,7 @@
                  + '  <div class="arrow"></div>\n'
                  + '  <h2 class="popover-title"></h2>\n'
                  + '  <div class="popover-content"></div>\n'
-                 + '  <div class="popover-navigation row">\n'
+                 + '  <div class="popover-navigation">\n'
                  + '    <div class="col-xs-6 text-left">\n';
     if (step.prev > -1) {
       template  += '      <a class="btn btn-default btn-sm" href="#" id="'+idPrefix+'_prev">#tr("tour.popover.previous")</a>\n';
@@ -606,6 +606,11 @@
   top: 3px;
   right: 5px;
 }
+
+.popover[class*="tour-"] .popover-navigation:not(.row) {
+  padding-right: 0;
+  padding-left: 0;
+}
 </code>
     </property>
     <property>