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.

lib/onebox/layout.rb

@@ -12,7 +12,7 @@ module Onebox
     attr_reader :view
 
     def initialize(name, record)
-      @record = Onebox::Helpers.symbolize_keys(record)
+      @record = record.deep_symbolize_keys
 
       # Fix any relative paths
       if @record[:image] && @record[:image] =~ %r{\A/[^/]}