Draft: Enable Secret Detection

What does this MR do?

Enables Secret Detection to help us detect accidental exposure of secrets such as API tokens and cryptographic keys in commits.

refs https://gitlab.com/gitlab-com/gl-security/appsec/appsec-team/-/issues/87

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

refs: https://gitlab.com/gitlab-com/gl-security/appsec/appsec-team/-/issues/87