lint: fix confusing comments in test vector file

Summary:
The --skip-arguments argument was removed in D2882, replaced by a FUNCTION_NAMES_AND_NUMBER_OF_LEADING_ARGUMENTS list.

Depends on D18221

Test Plan: python -m doctest test/lint/lint-format-strings.py

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D18222