Move to SAST_EXCLUDED_ANALYZERS
As part of gitlab-org/gitlab#290777 (closed), move away from SAST_DEFAULT_ANALYZERS and utilize SAST_EXCLUDED_ANALYZERS.
With latest changes, gemnasium
pipelines were failing: https://gitlab.com/gitlab-org/security-products/analyzers/gemnasium/-/pipelines/320487925
This should address those failures.