Make necessary changes to cacerts directories when using system openssl

In #6316 (closed) we will be adding the option for compiling omnibus gitlab with the system openssl rather than the bundled one.

We need to investigate whether we can still have the system openssl default to using our bundled certs directory by default.

If we cannot, we will need to investigate toggling where all the software is looking for the ssl certs from in the case of bundled ssl vs system ssl, and have a different path in our documentation for users wanting to add trusted certs. (which isn't ideal at this time)

Ideally we solve this as part of this issue, but depending how long the investigation takes, we may need to rename this to the investigation issue, and log a new issue for the next milestone for the investigation.