scripted-diff: Update copyright in ./test
Summary:
Partial backport of core PR14954 (commit faa7cdf):
https://github.com/bitcoin/bitcoin/pull/14954/commits/faa7cdf764a651975fa3c780df7df206a08254c2
Original scripted-diff for reference:
-BEGIN VERIFY SCRIPT- ./contrib/devtools/copyright_header.py update ./test/ -END VERIFY SCRIPT-
Test Plan:
Nop()
Reviewers: #bitcoin_abc, deadalnix, jasonbcox
Reviewed By: #bitcoin_abc, jasonbcox
Differential Revision: https://reviews.bitcoinabc.org/D4375