Release Environments - Automate Terraform part of GET with CI

Context

One Exit Criteria of &1567 (closed) is to deploy Release Environments (RE) using GET, so RE can support GitLab Geo setup.

In #21194 (closed), a prototype of GET was done, which helped us learn the right parameters we need to provide to GET to set up a Geo-supported GitLab setup.

Problem Statements

This issue aims at automating the Terraform step of setting up a Geo-supported GET setup. It inlcudes:

• Getting initial inputs (GitLab package version, credentials, etc.)
• Deploy the Primary setup
• Read the outputs of the Primary setup
• Deploy the Secondary setup

Exit Criteria

• The cloud resources of the Geo-supported GET setup are deployed using Terraform on CI pipeline