db: drop IP addresses from certain tables.

Don't track IP addresses for post appeals, post flags, tag aliases, tag
implications, or user feedbacks. These things are already tightly
limited. We don't need IPs from them to detect sockpuppets.

test/factories/tag_alias.rb

@@ -4,6 +4,5 @@ FactoryBot.define do
     consequent_name {"bbb"}
     status {"active"}
     skip_secondary_validations {true}
-    creator_ip_addr { FFaker::Internet.ip_v4_address }
   end
 end

test/unit/post_flag_test.rb

@@ -140,7 +140,6 @@ class PostFlagTest < ActiveSupport::TestCase
           PostFlag.create(:post => @post, :reason => "aaa", :is_resolved => false)
         end
         assert_equal(@alice.id, @post_flag.creator_id)
-        assert_equal(IPAddr.new("127.0.0.1"), @post_flag.creator_ip_addr)
       end
     end