Auto merge of #3239 - str4d:sapling-default-tx-version, r=str4d

Update CreateNewContextualCMutableTransaction for Sapling

Part of #3063.

src/rpcrawtransaction.cpp

@@ -455,7 +455,6 @@ UniValue createrawtransaction(const UniValue& params, bool fHelp)
         Params().GetConsensus(), nextBlockHeight);
     
     if (NetworkUpgradeActive(nextBlockHeight, Params().GetConsensus(), Consensus::UPGRADE_OVERWINTER)) {
-        rawTx.nExpiryHeight = nextBlockHeight + expiryDelta;
         if (rawTx.nExpiryHeight >= TX_EXPIRY_HEIGHT_THRESHOLD){
             throw JSONRPCError(RPC_INVALID_PARAMETER, "nExpiryHeight must be less than TX_EXPIRY_HEIGHT_THRESHOLD.");
         }