Lockdown ECS ALB to only allow Shared Services connections

[jpl-btlunsfo]

Purpose:

Restricting the previously completely open unity proxy ALB to only allow connections from the shared services account and proxy.

Changes

• ADD vpc peering connection lookups
• CHANGE original ALB SG ingress rules based on the returned information
• CHANGE ALB subnet and internal flags

Issues

• Lock down access of MC, so that outsiders with a URL cannot access it unity-cs#431
• Restrict Security Groups - CS unity-project-management#195

Testing

• Currently deployed here: https://www.dev.mdps.mcp.nasa.gov:4443/btl-dc1/dev/management/ui/landing

[jpl-btlunsfo]

Successfully deployed with security-group based restrictions! Should be available at: https://www.dev.mdps.mcp.nasa.gov:4443/btl-dc2/dev/management/ui/landing

Just to note though, since this endpoint is now locked down, it will no longer be available to check during run.sh, which means we'll probably need to update this line to use the shared services endpoint:
https://github.com/unity-sds/unity-cs-infra/blob/main/nightly_tests/run.sh#L353

[galenatjpl]

Looks good to me. Thanks!