Add env to toggle provider price syncs

app/models/security/provided.rb

@@ -29,6 +29,8 @@ module Security::Provided
   end
 
   def sync_provider_prices(start_date:, end_date: Date.current)
+    return 0 unless ENV["PROVIDER_PRICE_SYNC_ENABLED"] == "true"
+
     unless has_prices?
       Rails.logger.warn("Security id=#{id} ticker=#{ticker} is not known by provider, skipping price sync")
       return 0