Showcasing Config Difference Between Creating A New Project Vs Existing Project For Creation Of Migration Stack

[sujaysamanta]

This pull request updates the Terraform configuration for the stacks migration infrastructure, primarily focusing on project and stack naming, and introduces an import block for a specific project resource. These changes help clarify environment identification and enable resource management for an existing project.

Project and stack configuration updates:

• Changed the default value of the project_name variable to "Tf-Migrate-Stack-Migration-Retry-Test" in stacks_migration_infra/variables.tf to better reflect the purpose of the migration environment.
• Updated the default value of the stack_name variable to "hello-stacks-v5" in stacks_migration_infra/variables.tf for clearer stack identification.

Resource import for migration:

• Added an import block to stacks_migration_infra/main.tf to import the existing tfe_project.stack_project resource with ID "prj-XzHVjdCZnmdcPEDS", enabling Terraform to manage this resource going forward.