Adding default certificate to the certificate list for SNI client connections

[abeowlu]

Describe the feature you are requesting Scenarios in controller certificate auto-discovery;

• where different encryption certificate (ECC, RSA) are auto-discovered
• the ECC certificate is discovered first and in the LB model is created as the default certificate
• the RSA encyption certificate is discovered ...and any other certificate, and added to the certificate ilst
• From the ALB documentation, however, the default certificate is never used when a client request specifies the SNI and there is a certificate list
• client attempting to negotiate ECC cipher suite with an ALB only checking only the certificate list fails TLS negotiation

Motivation

• the ALB spec would seem to expect the default certificate to also be added to the certificate list

Describe the proposed solution you'd like

• Add the default certificate also to the certificate list. Perhaps appending the certificate twice?

Contribution Intention (Optional)

• Yes, I am willing to contribute a PR to implement this feature