Merge bitcoin#29998: functional test: ensure confirmed utxo being sourced for 2nd chain

07aba8d functional test: ensure confirmed utxo being sourced for 2nd chain (Greg Sanders)

Pull request description:

  The test could fail/stop testing what we want if non-confirmed utxos become sourced through some internal change to `MiniWallet`; better to just fetch confirmed explicitly.

ACKs for top commit:
  achow101:
    ACK 07aba8d
  ismaelsadeeq:
    utACK 07aba8d
  theStack:
    ACK 07aba8d

Tree-SHA512: 66795fdf881139ed91bde0f8239a46bd9bc70bb311fa97c0e2b5537e1fd2a1fd36bf3a225fc77b9695deb835a9d6d29879aa1e05ea5054b9a33a400e199da014

Author: achow101

test/functional/mempool_package_onemore.py

@@ -40,7 +40,7 @@ def run_test(self):
         for _ in range(DEFAULT_ANCESTOR_LIMIT - 4):
             utxo, = self.chain_tx([utxo])
             chain.append(utxo)
-        second_chain, = self.chain_tx([self.wallet.get_utxo()])
+        second_chain, = self.chain_tx([self.wallet.get_utxo(confirmed_only=True)])
 
         # Check mempool has DEFAULT_ANCESTOR_LIMIT + 1 transactions in it
         assert_equal(len(self.nodes[0].getrawmempool()), DEFAULT_ANCESTOR_LIMIT + 1)