Add example using ELB with multiple backends

What does this MR do?

Provides an example configuration for using an ELB to support both SSH and HTTPS with an HTTPS and TCP backend. It also provides a somewhat simple configuration for those who wish to get closer to an end-to-end encryption approach and don't want to go through the complications of layering a service mesh.

The two current examples make the user/customer choose between:

• Terminating at the ELB in layer 7 and using HTTP for all backend protocols, but then of course SSH doesn't work, which means you need another ELB / NLB for that
• Using layer 4 ELB and having to terminate at the end and manage certificates manually (or use cert-manager which has issues with pages).

This MR adds another option where the customer only has to worry bout managing self-signed certificates at the backend and gets the benefit of managed ACM certificates while also keeping SSH on the same DNS entry.

Related issues

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened