Prevent new Fetcher to retrieve the robots twice

The new Fetcher which is now used by default handles the robots file directly instead of relying on the protocol. The options Protocol.CHECK_BLOCKING and Protocol.CHECK_ROBOTS are set to false to prevent fetching the robots.txt twice (in Fetcher + in protocol), which avoids calling robots.isAllowed. However in practice the robots file is still fetched as there is a call to robots.getCrawlDelay() a bit further which is not covered by the if (Protocol.CHECK_ROBOTS).