[X-Pack] Update spec

Author: picandocodigo

elasticsearch-xpack/test/unit/monitoring/bulk_test.rb

@@ -14,7 +14,7 @@ class XPackMonitoringBulkTest < Minitest::Test
         should "perform correct request" do
           subject.expects(:perform_request).with do |method, url, params, body|
             assert_equal 'POST', method
-            assert_equal '_xpack/monitoring/_bulk', url
+            assert_equal '_monitoring/bulk', url
             assert_equal Hash.new, params
             assert_equal "", body
             true