UX: Stop putting usernames in edit reason when changing post owner

app/models/post.rb

@@ -546,13 +546,7 @@ class Post < ActiveRecord::Base
   def set_owner(new_user, actor, skip_revision = false)
     return if user_id == new_user.id
 
-    edit_reason = I18n.with_locale(SiteSetting.default_locale) do
-      I18n.t(
-        'change_owner.post_revision_text',
-        old_user: self.user&.username_lower || I18n.t('change_owner.deleted_user'),
-        new_user: new_user.username_lower
-      )
-    end
+    edit_reason = I18n.t('change_owner.post_revision_text', locale: SiteSetting.default_locale)
 
     revise(
       actor,

config/locales/server.en.yml

@@ -1868,8 +1868,7 @@ en:
       other: "%{count} posts were merged into an existing topic: %{topic_link}"
 
   change_owner:
-    post_revision_text: "Ownership transferred from %{old_user} to %{new_user}"
-    deleted_user: "a deleted user"
+    post_revision_text: "Ownership transferred"
 
   topic_statuses:
     archived_enabled: "This topic is now archived. It is frozen and cannot be changed in any way."

spec/models/post_spec.rb

@@ -1077,16 +1077,12 @@ describe Post do
 
     it "uses default locale for edit reason" do
       I18n.locale = 'de'
-      old_username = post.user.username_lower
 
       post.set_owner(coding_horror, Discourse.system_user)
       post.reload
 
       expected_reason = I18n.with_locale(SiteSetting.default_locale) do
-        I18n.t('change_owner.post_revision_text',
-               old_user: old_username,
-               new_user: coding_horror.username_lower
-        )
+        I18n.t('change_owner.post_revision_text')
       end
 
       expect(post.edit_reason).to eq(expected_reason)