Remove duplicate ImportCommonMetricsKnative migration

The EE port of
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9959 incorrectly
copied the same CE migration from
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24663 with a
different version, leading to a duplicate migration error.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/10963

db/migrate/20190405080345_import_common_metrics_knative.rb

-# frozen_string_literal: true
-
-class ImportCommonMetricsKnative < ActiveRecord::Migration[5.0]
-  include Gitlab::Database::MigrationHelpers
-
-  require Rails.root.join('db/importers/common_metrics_importer.rb')
-
-  DOWNTIME = false
-
-  def up
-    Importers::CommonMetricsImporter.new.execute
-  end
-
-  def down
-    # no-op
-  end
-end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20190405080345) do
+ActiveRecord::Schema.define(version: 20190404231137) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"