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/engine/gfycat_onebox.rb

@@ -76,7 +76,7 @@ module Onebox
         script = page.at_css('script[type="application/ld+json"]')
 
         if json_string = script&.text
-          @og_data = Onebox::Helpers.symbolize_keys(::MultiJson.load(json_string))
+          @og_data = ::MultiJson.load(json_string, symbolize_keys: true)
         else
           @og_data = {}
         end

lib/onebox/engine/imgur_onebox.rb

@@ -53,7 +53,7 @@ module Onebox
           rescue StandardError
             "{}"
           end
-        oembed_data = Onebox::Helpers.symbolize_keys(::MultiJson.load(response))
+        oembed_data = ::MultiJson.load(response, symbolize_keys: true)
         imgur_data_id = Nokogiri.HTML(oembed_data[:html]).xpath("//blockquote").attr("data-id")
         imgur_data_id.to_s[%r{a/}]
       end

lib/onebox/engine/vimeo_onebox.rb

@@ -34,7 +34,7 @@ module Onebox
 
       def oembed_data
         response = Onebox::Helpers.fetch_response("https://vimeo.com/api/oembed.json?url=#{url}")
-        @oembed_data = Onebox::Helpers.symbolize_keys(::MultiJson.load(response))
+        @oembed_data = ::MultiJson.load(response, symbolize_keys: true)
       rescue StandardError
         "{}"
       end