ha-autoscale-cluster: Enable proxy protocol to allow the use of IP pinning

[webvictim]

Changelog: Enabled the use of proxy protocol v2 for the ha-autoscale-cluster Terraform deployment example, allowing clusters deployed with this code to make use of IP pinning where needed.

Also:

• fixed a bug with the ACM LB name used when an alias was not provided
• made the connect.sh script more reliable by only targetting instances in running state

Fixes #34284

Test matrix:

use_acm	use_tls_routing	auth_service proxy_protocol	proxy_service proxy_protocol	LBs deployed
false	false	on	on	auth: NLB, proxy: NLB
true	false	on	not set	auth: NLB, proxy: ALB + NLB
false	true	on	on	auth: NLB, proxy: NLB
true	true	on	not set	auth: NLB, proxy: ALB

proxy_protocol does not need to be set to on when an ALB is used, as proxy_service.trust_x_forwarded_for is set to true in these situations and the client IP is derived from the X-Forwarded-For header.

The starter-cluster deployment only deploys an ALB when ACM is enabled, so remains unchanged.

[public-teleport-github-review-bot]

@webvictim See the table below for backport results.

Branch	Result
branch/v16	Create PR