users: don't log mod action for user deletions.

Don't log a mod action when a user deletes their own account. This isn't a moderator action, so it
doesn't belong here. Account deletions are still logged on the /user_events page (visible to mods only).

A mod action is still logged when the Owner-level user deletes someone else's account.

app/logical/user_deletion.rb

@@ -34,7 +34,7 @@ class UserDeletion
       rename
       reset_password
       async_delete_user
-      ModAction.log("deleted user ##{user.id}", :user_delete, subject: user, user: deleter)
+      ModAction.log("deleted user ##{user.id}", :user_delete, subject: user, user: deleter) if user != deleter
       UserEvent.create_from_request!(user, :user_deletion, request) if request.present?
       SessionLoader.new(request).logout(user) if user == deleter
     end

test/unit/user_deletion_test.rb

@@ -84,13 +84,10 @@ class UserDeletionTest < ActiveSupport::TestCase
       assert_equal(false, @user.authenticate_password("password"))
     end
 
-    should "generate a modaction" do
+    should "not generate a modaction" do
       @deletion.delete!
 
-      assert_match(/deleted user ##{@user.id}/, ModAction.last.description)
-      assert_equal(@user, ModAction.last.subject)
-      assert_equal("user_delete", ModAction.last.category)
-      assert_equal(@deletion.deleter, ModAction.last.creator)
+      assert_equal(0, ModAction.user_delete.count)
     end
 
     should "remove the user's favorites if they have private favorites" do