change block_number to hex string

[nicodechal]

In Smallbank benchmark, change block_number to hex string like YCSB benchmark to avoid request error:
https://github.com/nicodechal/blockbench/blob/ae833572c16d60f76fd3b249f93a4517336e19ee/src/macro/kvstore/core/evm_utils.cc#L289-L291

and then I found in poll_txs_by_block_number, uncle in uncles already has quotes, But GET_BLOCK_BY_HASH_PREFIX gives uncle one more pair of quotes, so I remove the quotes of uncle to make it run correct. If this is true, then YCSB benchmark also need to be modified.

[ug93tad]

Thanks for the PR.

• Ethereum eth_getBlockByNumber take a decimal representation as well as hex, so the current implementation still works.

• The quote was already removed in the StatusThread in smallbank.cc file.

[nicodechal]

@ug93tad

• I tested with go-ethereum v1.8.16 and I got only zero results like I mentioned in Question about running ethereum's macro benchmark using Smallbank workload #51 (comment) with decimal blocknumber use Smallbank workload.
  The Error I got like this:

{
  "jsonrpc":"2.0",
  "id":1,
  "error": { 
    "code": -32602,
    "message": "invalid argument 0: hex string without 0x prefix"
  }
}

• and the quote I removed is different with the quote in StatusThread. The hash I removed quote is uncle's and it's used to find uncle block with poll_txs_by_block_hash, while removing quote in StatusThread is for counting.
  The Error I got:

{
  "jsonrpc":"2.0",
  "error":  {
    "code":-32600,
    "message": "invalid character '0' after array element"
  }
}