models: stop saving IP addresses in version tables.

Mark various `creator_ip_addr` and `updater_ip_addr` columns as ignored
and stop updating them in preparation for dropping them.

app/models/application_record.rb

@@ -191,7 +191,6 @@ class ApplicationRecord < ActiveRecord::Base
           belongs_to :updater, class_name: "User", **options
           before_validation do |rec|
             rec.updater_id = CurrentUser.id
-            rec.updater_ip_addr = CurrentUser.ip_addr if rec.respond_to?(:updater_ip_addr=)
           end
         end
       end