message: rpc: Remove deprecated "size" from mempool txs
  Remove the "size" property of a mempool transaction from RPC replies.
  Deprecated in in 0.19, about 1 year ago.
diff: @@ -392,8 +392,6 @@ static UniValue getdifficulty(const JSONRPCRequest& request)
  static std::vector<RPCResult> MempoolEntryDescription() { return {
  RPCResult{RPCResult::Type::NUM, "vsize", "virtual transaction size as defined in BIP 141. This is different from actual serialized size for witness transactions as witness data is discounted."},
  - RPCResult{RPCResult::Type::NUM, "size", "(DEPRECATED) same as vsize. Only returned if bitcoind is started with -deprecatedrpc=size\n"
  - "size will be completely removed in v0.20."},
  RPCResult{RPCResult::Type::NUM, "weight", "transaction weight as defined in BIP 141."},
  RPCResult{RPCResult::Type::STR_AMOUNT, "fee", "transaction fee in " + CURRENCY_UNIT + " (DEPRECATED)"},
  RPCResult{RPCResult::Type::STR_AMOUNT, "modifiedfee", "transaction fee with fee deltas used for mining priority (DEPRECATED)"},
  @@ -431,7 +429,6 @@ static void entryToJSON(const CTxMemPool& pool, UniValue& info, const CTxMemPool
  info.pushKV("fees", fees);
  info.pushKV("vsize", (int)e.GetTxSize());
  - if (IsDeprecatedRPCEnabled("size")) info.pushKV("size", (int)e.GetTxSize());
  info.pushKV("weight", (int)e.GetTxWeight());
  info.pushKV("fee", ValueFromAmount(e.GetFee()));
  info.pushKV("modifiedfee", ValueFromAmount(e.GetModifiedFee()));
  