Get the GCP project_id for terratest from terraform.tfvars file

[za]

Issue #2070

[bendehaan]

LGTM, thanks again!

[za]

Thanks for reviewing and merging it @bendehaan

I can see it's working now, after I set the project_id on terraform.tfvars:

$ go test -timeout 999999s

TestTerraformWrongSecretsGCP 2025-06-25T11:40:05+07:00 logger.go:67: ╵
TestTerraformWrongSecretsGCP 2025-06-25T11:40:05+07:00 logger.go:67:
TestTerraformWrongSecretsGCP 2025-06-25T11:40:05+07:00 logger.go:67: Destroy complete! Resources: 21 destroyed.
TestTerraformWrongSecretsGCP 2025-06-25T11:40:05+07:00 logger.go:67: 
PASS
ok      wrongsecrets    1283.974s