Use AZ CLI to clean up Terraform nightly deployments

[brooke-hamilton]

Benefit/Result/Outcome

So that nightly deployments of Terraform run with fewer spurious errors.

Description

The nightly Terraform build is often failing due to errors running the terraform destroy command. The errors are due to either issues in the Azure RM provider for Terraform, Terraform itself, or Azure. The errors are not related to Mission Landing Zone code, so rather than try to fix them we can use AZ CLI commands to clean up the build artifacts rather than terraform destroy.

Refer to the Bicep cleanup instructions for how to delete all MLZ resources using the AZ CLI.

This is related to #609

Acceptance Criteria

• The nightly Terraform deployments use AZ CLI commands to clean up deployed resources.