Use COINBASE_MATURITY constant in functional tests.

test/functional/mempool_resurrect.py

@@ -4,6 +4,7 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test resurrection of mined transactions when the blockchain is re-organized."""
 
+from test_framework.blocktools import COINBASE_MATURITY
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal
 from test_framework.wallet import MiniWallet
@@ -20,7 +21,7 @@ class MempoolCoinbaseTest(BitcoinTestFramework):
 
         # Add enough mature utxos to the wallet so that all txs spend confirmed coins
         wallet.generate(3)
-        node.generate(100)
+        node.generate(COINBASE_MATURITY)
 
         # Spend block 1/2/3's coinbase transactions
         # Mine a block