Run Pre-commit Secret Detection scans within Subprocess

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/139053



Merged-by: Lucas Charles <me@lucascharles.me>
Approved-by: Lucas Charles <me@lucascharles.me>
Approved-by: Ahmed Hemdan <ahemdan@gitlab.com>
Reviewed-by: Lucas Charles <me@lucascharles.me>
Reviewed-by: Vishwa Bhat <vbhat@gitlab.com>
Reviewed-by: Ahmed Hemdan <ahemdan@gitlab.com>
Co-authored-by: Vishwa Bhat <vbhat@gitlab.com>