Enable debug in downstream pipelines

What does this MR do?

Set SECURE_LOG_LEVEL to debug in downstream pipelines used for QA.

SECURE_LOG_LEVEL defaults to info. Forcing it to debug makes possible to catch bugs triggered when logging messages with functions like log.Debug. Also, we can check the debug messages, and make sure they're well presented.

To illustrate, when working on gitlab-org/security-products/analyzers/gemnasium!82 (comment 372674838) with @dsearles, I caught a bug when forcing the log level to debug, but this bug went unnoticed in the automatic QA, in the downstream pipelines.

What are the relevant issue numbers?

gitlab-org/gitlab#10880 (closed)

Does this MR meet the acceptance criteria?

• [-] Tests added for this feature/bug

This has been tested manually with https://gitlab.com/gitlab-org/security-products/analyzers/gemnasium/-/pipelines/162915807. See https://gitlab.com/gitlab-org/security-products/tests/js-yarn/-/jobs/623305781