UX: Replace Google search with Discourse search on not found page

* UX: Replace Google search with Discourse search on not found page.

* FIX: Update application_controller_spec.rb.

app/controllers/application_controller.rb

@@ -700,7 +700,7 @@ class ApplicationController < ActionController::Base
     @slug =  params[:slug].class == String ? params[:slug] : ''
     @slug =  (params[:id].class == String ? params[:id] : '') if @slug.blank?
     @slug.tr!('-', ' ')
-    @hide_google = true if SiteSetting.login_required
+    @hide_search = true if SiteSetting.login_required
     render_to_string status: status, layout: layout, formats: [:html], template: '/exceptions/not_found'
   end
 

app/controllers/exceptions_controller.rb

@@ -1,6 +1,6 @@
 class ExceptionsController < ApplicationController
   skip_before_action :check_xhr, :preload_json
-  before_action :hide_google
+  before_action :hide_search
 
   def not_found
     # centralize all rendering of 404 into app controller
@@ -14,8 +14,8 @@ class ExceptionsController < ApplicationController
 
   private
 
-  def hide_google
-    @hide_google = true if SiteSetting.login_required
+  def hide_search
+    @hide_search = true if SiteSetting.login_required
   end
 
 end

app/views/exceptions/not_found.html.erb

@@ -25,15 +25,14 @@
   </div>
 <% end %>
 
-<%- unless @hide_google %>
+<%- unless @hide_search%>
   <div class="row">
     <div class="page-not-found-search">
       <h2><%= t 'page_not_found.search_title' %></h2>
       <p>
-        <form action='//google.com/search' id='google-search'>
+        <form action='/search' id='discourse-search'>
           <input type="text" name="q" value="<%= @slug %>">
-          <input type='hidden' name="as_sitesearch" value="<%= Discourse.base_url %>">
-          <button class="btn btn-primary"><%= t 'page_not_found.search_google' %></button>
+          <button class="btn btn-primary"><%= t 'page_not_found.search_button' %></button>
         </form>
       </p>
     </div>

config/locales/server.en.yml

@@ -3165,7 +3165,7 @@ en:
     recent_topics: "Recent"
     see_more: "More"
     search_title: "Search this site"
-    search_google: "Google"
+    search_button: "Search"
 
   offline:
     title: "Cannot load app"

spec/requests/application_controller_spec.rb

@@ -68,7 +68,7 @@ RSpec.describe ApplicationController do
       it 'should return 404 and show Google search' do
         get "/t/nope-nope/99999999"
         expect(response.status).to eq(404)
-        expect(response.body).to include(I18n.t('page_not_found.search_google'))
+        expect(response.body).to include(I18n.t('page_not_found.search_button'))
       end
 
       it 'should not include Google search if login_required is enabled' do