Drop column instance_statistics_visibility_private

After it has been ignored and is no longer needed

changelogs/unreleased/drop-instance-statistics-visibility-private-column.yml

+---
+title: Drop column instance_statistics_visibility_private
+merge_request: 42969
+author:
+type: deprecated

db/post_migrate/20200922095954_remove_instance_statistics_visibility_private_from_application_settings.rb

+# frozen_string_literal: true
+
+class RemoveInstanceStatisticsVisibilityPrivateFromApplicationSettings < ActiveRecord::Migration[6.0]
+  DOWNTIME = false
+
+  def up
+    remove_column :application_settings, :instance_statistics_visibility_private
+  end
+
+  def down
+    add_column :application_settings, :instance_statistics_visibility_private, :boolean, default: false, null: false
+  end
+end

db/schema_migrations/20200922095954

+c55f27f817afc60462e5dc43755a4ddd76f1399f5e461bab4b36bf5e5b26ce0a
\ No newline at end of file

db/structure.sql

@@ -9146,7 +9146,6 @@ CREATE TABLE application_settings (
     snowplow_enabled boolean DEFAULT false NOT NULL,
     snowplow_collector_hostname character varying,
     snowplow_cookie_domain character varying,
-    instance_statistics_visibility_private boolean DEFAULT false NOT NULL,
     web_ide_clientside_preview_enabled boolean DEFAULT false NOT NULL,
     user_show_add_ssh_key_message boolean DEFAULT true NOT NULL,
     custom_project_templates_group_id integer,