Merge #19781: test: add parameterized constructor for msg_sendcmpct()

638441928a test: add parameterized constructor for msg_sendcmpct() (Sebastian Falbesoner)

Pull request description:

  While working on the test for #19776 I noticed that creating a `sendcmpct` message is quite cumbersome -- due to the lack of a parameterized constructor, one needs to create an empty (that is, initialized with default values) object and then set the two fields one by one. This PR replaces the default constructor with a parameterized constructor and uses it in the test `p2p_compactblocks.py`, reducing LOC. No need to pollute the namespace with temporary throw-away message objects anymore.

ACKs for top commit:
  guggero:
    Code review ACK 638441928a.
  epson121:
    Code review ACK 638441928a

Tree-SHA512: 3b58d276d714b73abc6cc98d1d52dec5f6026b33f03faaeb7dcbc5d83ac377555179f98b159b2b9ecc8957999c35a1dc082e3c69299c5fde4e35f1bd0587ce9d

test/functional/test_framework/messages.py

@@ -1472,9 +1472,9 @@ class msg_sendcmpct:
     __slots__ = ("announce", "version")
     msgtype = b"sendcmpct"
 
-    def __init__(self):
-        self.announce = False
-        self.version = 1
+    def __init__(self, announce=False, version=1):
+        self.announce = announce
+        self.version = version
 
     def deserialize(self, f):
         self.announce = struct.unpack("<?", f.read(1))[0]