Spidermon logs are not properly uploaded

[rennerocha]

Some Spidermon built-in monitors (like ItemValidationMonitor) increases the size of the stats logged, and because when trying to upload that to Scrapy Cloud, we receive a "Value exceeds max encoded size of 65536 bytes" error message.

One solution suggested was to remove the stats in Spidermon based on a new setting. However, the size limitation is neither Spidermon nor a Scrapy problem, as we don't have limits in how we can use the stats in both libraries.

It is a limitation in a vendor tool (Scrapy Cloud), so one possible solution is to update HubStorageStatsCollector that is the Stats Collector used by Scrapy Cloud to handle this scenario.