Adds dependency_proxy_size to root storage stats

To enable efficiently storing the total dependency proxy storage size
at the root level storage statistics

Changelog:added

db/migrate/20220119144253_add_dependency_proxy_size_to_namespace_root_storage_statistics.rb

+# frozen_string_literal: true
+
+class AddDependencyProxySizeToNamespaceRootStorageStatistics < Gitlab::Database::Migration[1.0]
+  def change
+    add_column :namespace_root_storage_statistics, :dependency_proxy_size, :bigint, default: 0, null: false
+  end
+end

db/schema_migrations/20220119144253

+723db0d234a4dadfdad68a92c249ec0b42e519297f48bcb843e89c1ad97032c7
\ No newline at end of file

db/structure.sql

@@ -16509,7 +16509,8 @@ CREATE TABLE namespace_root_storage_statistics (
     packages_size bigint DEFAULT 0 NOT NULL,
     snippets_size bigint DEFAULT 0 NOT NULL,
     pipeline_artifacts_size bigint DEFAULT 0 NOT NULL,
-    uploads_size bigint DEFAULT 0 NOT NULL
+    uploads_size bigint DEFAULT 0 NOT NULL,
+    dependency_proxy_size bigint DEFAULT 0 NOT NULL
 );
 
 CREATE TABLE namespace_settings (