message: [validation] default conflicting fees and size to 0
  This should have no effect in practice, since we only ever call
  PreChecks once per transaction.
diff: @@ -465,8 +465,10 @@ private:
  bool m_replacement_transaction;
  CAmount m_base_fees;
  CAmount m_modified_fees;
  - CAmount m_conflicting_fees;
  - size_t m_conflicting_size;
  + /** Total modified fees of all transactions being replaced. */
  + CAmount m_conflicting_fees{0};
  + /** Total virtual size of all transactions being replaced. */
  + size_t m_conflicting_size{0};
  const CTransactionRef& m_ptx;
  const uint256& m_hash;
  