Update the testsuite to make use of the utilities for certificate generation instead of using pre-generated CAs and certs

Our testsuite currently makes use of pre-generated CAs and certs. This results in issues when the certificates expire since the testsuite then needs to be updated with newly generated CAs and certs. This task is to update our testsuite to dynamically generate the needed certificates using Elytron's certificate generation utilities (e.g., org.wildfly.security.x500.cert.X509CertificateBuilder, org.wildfly.security.x500.cert.SelfSignedX509CertificateAndSigningKey.builder(), etc.).