DEV: Replace custom Onebox symbolize_keys implementation with ActiveSupport (#23828)

We have a custom implementation of #symbolize_keys in our Onebox helpers. This is likely a legacy from when Onebox was a standalone gem. This change replaces all usages with either #deep_symbolize_keys from ActiveSupport, or appropriate option to the JSON parser gem used.

spec/lib/onebox/engine/google_maps_onebox_spec.rb

@@ -72,7 +72,7 @@ RSpec.describe Onebox::Engine::GoogleMapsOnebox do
     end
   end
 
-  let(:data) { Onebox::Helpers.symbolize_keys(onebox.send(:data)) }
+  let(:data) { onebox.send(:data).deep_symbolize_keys }
   let(:link) { |example| URLS[example.metadata[:urltype] || :short][:test] }
 
   include_context "an engine", urltype: :short