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.

test/factories/dmail.rb

@@ -3,7 +3,6 @@ FactoryBot.define do
     owner factory: :user
     from factory: :user
     to factory: :user
-    creator_ip_addr { FFaker::Internet.ip_v4_address }
     title {FFaker::Lorem.words.join(" ")}
     body {FFaker::Lorem.sentences.join(" ")}
   end