fix(tf-checks): load environment variables for Terraform checks

[kalyani-cd]

Summary

This PR updates the tf-check workflow to load required environment variables from the env-vars secret before running Terraform checks.

Changes

• Added support for the env-vars secret in the tf-check workflow.
• Added a step to export environment variables to $GITHUB_ENV.
• Ensures required environment variables are available during Terraform validation and plan execution.
• Avoids hardcoding environment-specific values in the Terraform module.

[pendharevaibhav-cd]

LGTM!