Prevent Rails filtered parameters from leaking to Sentry.

As described in their Docs: https://docs.getsentry.com/on-premise/clients/ruby/integrations/rails/

config/initializers/sentry.rb

@@ -15,6 +15,9 @@ if Rails.env.production?
     Raven.configure do |config|
       config.dsn = current_application_settings.sentry_dsn
       config.release = Gitlab::REVISION
+      
+      # Sanitize fields based on those sanitized from Rails.
+      config.sanitize_fields = Rails.application.config.filter_parameters.map(&:to_s)
     end
   end
 end