HUE-8218 [search] Remove the dropdown of choice of engines in new dashboard

Keep it similar to the Editor, where the language simplify comes from the menu
and remove some of the noise on the new dashboard page.

desktop/libs/dashboard/src/dashboard/templates/common_search.mako

@@ -63,13 +63,6 @@ from dashboard.conf import USE_GRIDSTER, HAS_REPORT_ENABLED, HAS_WIDGET_FILTER,
     </div>
     <div class="search-bar-middle">
       <form class="form-search" data-bind="visible: $root.isEditing() && columns().length == 0, submit: function() { return false }">
-        <!-- ko if: $root.initial.engines().length > 1 -->
-        <select class="input-medium" data-bind="options: $root.initial.engines, value: $root.collection.engine, optionsText: 'name',  optionsValue: 'type', disable: isSyncingCollections"></select>
-        <!-- /ko -->
-        <!-- ko ifnot: $root.initial.engines().length > 1 -->
-        ${_('index')}
-        <!-- /ko -->
-
         <!-- ko if: $root.collection.engine() == 'solr' -->
         <!-- ko if: columns().length == 0 -->
         <select data-bind="selectize: $root.initial.collections.sort(), value: $root.collection.name, disable: isSyncingCollections, selectizeOptions: { clearable: true }"></select>