Update environment variable GOOGLE_CLOUD_KEYFILE_JSON

[slevenick]

Upstreams hashicorp/terraform-provider-google#6397

Release Note Template for Downstream PRs (will be copied)

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[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 1 file changed, 2 insertions(+), 2 deletions(-))
Terraform Beta: Diff ( 1 file changed, 2 insertions(+), 2 deletions(-))