[CMAKE] Set environment variables when running tests with sanitizers

Summary:
This will allow to run the tests with sanitizers settings (such as
suppression files and various options) automatically set.

Test Plan:

cmake -GNinja .. -DENABLE_SANITIZERS=undefined # Use any sanitizer
ninja check check-functional

cmake .. -DENABLE_SANITIZERS=undefined # Use any sanitizer
make -j42 check check-functional

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D5689