Fix CNode construction in fuzz tests

Summary: This is a follow up for D10973. The CNode constructors were not updated in the fuzz tests.

Test Plan:

ninja bitcoin-fuzzers
./src/test/fuzz/process_message <path/to/corpus>/process_message
./src/test/fuzz/process_messages <path/to/corpus>/process_messages

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D10989