key: 0x02 | sdk.Uint64ToBigEndian(blockNumber) -> sdk.Uint64ToBigEndian(value)
storing used bandwidth for each block
used for calculation of load using sum of used bandwidth in blocks
at recovery period window
used for reverting transactions with cyberlinks if rise more than max block bandwidth
sdk.Uint64ToBigEndian(value) // where value is amount of bandwidth used by all neurons in given block