REFACTOR: admin plugins controller specs to requests (#5977)

spec/requests/admin/plugins_controller_spec.rb

@@ -7,13 +7,14 @@ describe Admin::PluginsController do
   end
 
   context "while logged in as an admin" do
-    let!(:admin) { log_in(:admin) }
+    before do
+      sign_in(Fabricate(:admin))
+    end
 
     it 'should return JSON' do
-      get :index, format: :json
+      get "/admin/plugins.json"
       expect(response.status).to eq(200)
       expect(::JSON.parse(response.body).has_key?('plugins')).to eq(true)
     end
   end
-
 end