Enable query string quantization by default

This change is mandated by the unifying tag RFC.

lib/datadog/tracing/contrib/rack/configuration/settings.rb

@@ -37,7 +37,7 @@ class Settings < Contrib::Configuration::Settings
             option :distributed_tracing, default: true
             option :headers, default: DEFAULT_HEADERS
             option :middleware_names, default: false
-            option :quantize, default: {}
+            option :quantize, default: { query: { show: :all } }
             option :request_queuing, default: false
 
             option :service_name