Make keep typing dropdown item static

app/assets/javascripts/filtered_search/dropdown_hint.js.es6

@@ -3,10 +3,6 @@
 
 ((global) => {
   const dropdownData = [{
-    icon: 'fa-search',
-    hint: 'Keep typing and press Enter',
-    tag: '',
-  },{
     icon: 'fa-pencil',
     hint: 'author:',
     tag: '<author>'

app/views/shared/issuable/_search_bar.html.haml

@@ -16,7 +16,14 @@
           = icon('filter')
           %button.clear-search.hidden{ type: 'button' }
             = icon('times')
-          %ul#js-dropdown-hint.dropdown-menu.hint-dropdown{ 'data-dynamic' => true }
+          #js-dropdown-hint.dropdown-menu.hint-dropdown
+            %ul
+              %li.filter-dropdown-item{ 'data-value': 'none' }
+                %button.btn.btn-link
+                  = icon('search')
+                  %span
+                    Keep typing and press Enter
+            %ul.filter-dropdown{ 'data-dynamic' => true }
               %li.filter-dropdown-item
                 %button.btn.btn-link
                   %i.fa{ 'class': '{{icon}}'}