[Tests] Rename create_tx and move to blocktools.py

test/functional/mempool_spend_coinbase.py

@@ -13,6 +13,7 @@ but less mature coinbase spends are NOT.
 """
 
 from test_framework.test_framework import BitcoinTestFramework
+from test_framework.blocktools import create_raw_transaction
 from test_framework.util import *
 
 # Create one-input, one-output, no-fee transaction:
@@ -31,7 +32,7 @@ class MempoolSpendCoinbaseTest(BitcoinTestFramework):
         # is too immature to spend.
         b = [ self.nodes[0].getblockhash(n) for n in range(101, 103) ]
         coinbase_txids = [ self.nodes[0].getblock(h)['tx'][0] for h in b ]
-        spends_raw = [ create_tx(self.nodes[0], txid, node0_address, 49.99) for txid in coinbase_txids ]
+        spends_raw = [ create_raw_transaction(self.nodes[0], txid, node0_address, 49.99) for txid in coinbase_txids ]
 
         spend_101_id = self.nodes[0].sendrawtransaction(spends_raw[0])