Gitlab QA: Switching to using a root certificate

Counterpart MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/54799

Root Certificate Authority

The goal of this change is to clean up any certificate related scenarios.

Removing the need for trusting self-signed certificates

I removed the need to trust self-signed certificates by creating my own certificate authority that can be trusted by any system and thus any certificate request that is signed by this authority is automatically trusted by the host.

After a review of the current setup, I had to have new certificates that are all signed by one Certification Authority. This makes it possible to have a central authority that we can add to the root certificates of every instance and thus trust it by default. For client authentication this way is the closest to a real live usage of this feature.

Node	File	Creation Command
CA	ca.key	openssl genrsa -out ca.key 4096
CA	ca.crt	openssl req -new -x509 -days 3650 -key ca.key -out ca.crt
CA	ca.pem	cat ca.key ca.crt > ca.pem
GitLab	gitlab.test.key	openssl genrsa -out gitlab.test.key 4096
GitLab	gitlab.test.csr	openssl req -new -key gitlab.test.key -out gitlab.test.csr
GitLab	gitlab.test.crt	openssl x509 -req -days 3650 -in gitlab.test.csr -CA ca.crt -CAkey ca.key -set_serial 1 -out gitlab.test.crt
Gitaly	gitaly.test.key	openssl genrsa -out gitaly.test.key 4096
Gitaly	gitaly.test.csr	openssl req -new -key gitaly.test.key -out gitaly.test.csr
Gitaly	gitaly.test.crt	openssl x509 -req -days 3650 -in gitaly.test.csr -CA ca.crt -CAkey ca.key -set_serial 1 -out gitaly.test.crt

The subject for the nodes is kept simple and consists of:

subject=C = US, ST = California, L = San Francisco, O = <Node> Server, CN = <node>.test

Similarly, the subject for the authority is:

subject=C = US, ST = California, L = San Francisco, O = GitLab Authority

Cleaning up old scenarios

There were two old scenarios that are based on SSL and use it on their test setup. These are LDAP with TLS and mTLS between GitLab and Gitaly. Since there is no need for trusting some self-signed certificate if the specs image is already trusting our GitLab Authority, I removed this call from the scenario.

I also cleaned up the volume linking on the components gitlab and specs. We do not need to trust the certificates of the servers any more by putting them in the trusted-certs folder. They are all signed by our authority and thus by trusting the authority, we trust the server certificates.

A good way to understand this is: The gitaly server does not need to have a copy of the gitlab server ID for comparison, when gitlab server has a signed document by the authority, and gitaly knows that signature to be correct. gitaly trusts the authority, so this is enough.