[EOSIO/eos] split blocks.log (#5322)

Theoretically it should be able to store in even a single file, as the max block size is around 1MB and around 60M blocks/year, which would be 60TB/year at maximum. So having a RAID 0 config for 4 14TB harddisks can allow you to store the whole log for years. What’s your harddisk size and your current blocks.log size?