What would you like Teleport to do?

Use the IAM joining method in the ha-autoscale-cluster instead of the ugly machinery we have that renews token.

What problem does this solve?

• no shared secrets, more secure
• more reliable joining, fewer failure modes
• no longer "proxy takes 20 minutes to start because it's waiting for a token" after initial deployment (encountered this during the test plan as I rolled the auths a bit too quickly)

If a workaround exists, please include it.

• keep using the static token rotation system we build before IAM joining was a thing

Implementation notes:

• do we want to leave the scripts in place for users of the old TF code or are we OK with pushing a breaking change in the AMI?
• Would fix ExecStartPre systemd prevents teleport from start #4803
• We can use the --apply-on-startup flag to create the proxy token