message: qa: Fix bug introduced in p2p-segwit.py
  Changing __init__() -> set_test_params() in the tests should not have
  applied to NodeConnCB-derived objects.
  Github-Pull:
  Rebased-From:
diff: @@ -33,8 +33,8 @@ def get_virtual_size(witness_block):
  return vsize
  class TestNode(NodeConnCB):
  - def set_test_params(self):
  - self.num_nodes = 3
  + def __init__(self):
  + super().__init__()
  self.getdataset = set()
  def on_getdata(self, conn, message):
  