Original script:
```
-BEGIN VERIFY SCRIPT-
./contrib/devtools/copyright_header.py update ./src/bench/
./contrib/devtools/copyright_header.py update ./src/test/
-END VERIFY SCRIPT-
```
Completes backport of core PR15788:
https://github.com/bitcoin/bitcoin/pull/15788/commits/faf400077d0144363c2dd24187431d958fb149a9
Depends on D5494.
Subset of test files only for ease of review.