[CI] Enable debug for the ASAN build

Summary:
This kills 2 birds with one stone:

• Make the CI run the tests with debug enabled, which was not the case

yet;

• Provide the stack trace with symbols in case of ASAN failure.

Depends on D3740

Test Plan: Run the CI build-asan config.

Reviewers: #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D3741