Add real valid certificates here for real cert based tests.
The certificate and key files have to be in PEM format and their names have to start with the same string and end in "_cert.pem" and "_key.pem"
For example, "tlstest_2023-07-02_cert.pem" and "tlstest_2023-07-02_key.pem"
You can also have multiple real certificates from different issuers.