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/support/onebox_helpers.rb

@@ -22,7 +22,7 @@ module OneboxHelpers
 
     let(:onebox) { described_class.new(link) }
     let(:html) { onebox.to_html }
-    let(:data) { Onebox::Helpers.symbolize_keys(onebox.send(:data)) }
+    let(:data) { onebox.send(:data).deep_symbolize_keys }
     let(:link) { @link }
   end