test: remove ToHex helper, use .serialize().hex() instead

test/functional/test_framework/messages.py

@@ -196,11 +196,6 @@ def FromHex(obj, hex_string):
     return obj
 
 
-# Convert a binary-serializable object to hex (eg for submission via RPC)
-def ToHex(obj):
-    return obj.serialize().hex()
-
-
 def tx_from_hex(hex_string):
     """Deserialize from hex string to a transaction object"""
     return FromHex(CTransaction(), hex_string)