Move make check test logs out of tree

Summary:
Thanks to @deadalnix for pointing out the issue.

Follow-up for D3535.

When running make check all the tests output a <test_file>.log file
to the src/test/ directory (in tree).
This diffs moves these logs to the <build_dir>/src/test/ directory
(out of tree) with the name <test_file>.test.log.

Test Plan:

mkdir build && cd build
make check

Ensure the test logs are in the correct place.

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D3591