Add support to disable FIPS mode via env var

This merge request considers the edge case where GitLab is deployed on a FIPS enabled environment (k8s cluster), but the administrator does not want GitLab to assume FIPS mode because it restricts capabilities required by the administrator. Such a case is the desire to have Personal and Project Access Tokens available for API access with GitLab as other alternatives are not available or clearly documented.

Being able to disable FIPS_MODE via an environment variable saves the user a configuration nightmare with k8s environments that require him/her to enable unsafe sysctls for the securityContext of pods. The referenced unsafe sysctl is crypto.fips_enabled.