Use generate* from TestFramework

The changes in feature_rbf can be reviewed with
--color-moved=dimmed-zebra --color-moved-ws=ignore-all-space

test/functional/mining_prioritisetransaction.py

@@ -48,7 +48,7 @@ class PrioritiseTransactionTest(BitcoinTestFramework):
         self.relayfee = self.nodes[0].getnetworkinfo()['relayfee']
 
         utxo_count = 90
-        utxos = create_confirmed_utxos(self.relayfee, self.nodes[0], utxo_count)
+        utxos = create_confirmed_utxos(self, self.relayfee, self.nodes[0], utxo_count)
         base_fee = self.relayfee*100 # our transactions are smaller than 100kb
         txids = []