Remove unused #hash_to_object method in SettingsHelper (#25213)

spec/lib/hash_object_spec.rb

@@ -1,9 +0,0 @@
-# frozen_string_literal: true
-
-require 'rails_helper'
-
-describe HashObject do
-  it 'has methods corresponding to hash properties' do
-    expect(HashObject.new(key: 'value').key).to eq 'value'
-  end
-end