Add migration to remove projects.container_registry_enabled

The projects.container_registry_enabled column has been replaced by
the project_features.container_registry_access_level column.

Changelog: removed

db/post_migrate/20210909152027_remove_container_registry_enabled.rb

+# frozen_string_literal: true
+
+class RemoveContainerRegistryEnabled < Gitlab::Database::Migration[1.0]
+  disable_ddl_transaction!
+
+  def up
+    with_lock_retries do
+      remove_column :projects, :container_registry_enabled
+    end
+  end
+
+  def down
+    with_lock_retries do
+      add_column :projects, :container_registry_enabled, :boolean # rubocop:disable Migration/AddColumnsToWideTables
+    end
+  end
+end

db/schema_migrations/20210909152027

+abed3f9a6c188890d3dcd21f73a09347f8ccec0f6cc448220fadba5cbda17281
\ No newline at end of file

db/structure.sql

@@ -18172,7 +18172,6 @@ CREATE TABLE projects (
     public_builds boolean DEFAULT true NOT NULL,
     last_repository_check_failed boolean,
     last_repository_check_at timestamp without time zone,
-    container_registry_enabled boolean,
     only_allow_merge_if_pipeline_succeeds boolean DEFAULT false NOT NULL,
     has_external_issue_tracker boolean,
     repository_storage character varying DEFAULT 'default'::character varying NOT NULL,