fix: fix default tofu unpacking

[pivotal-marcela-campo]

We are keeping the default provider registry as terraform's own registry for now instead of switching to terraform. We had done this during pak but had still defaulting to opentofu registry when unpacking which caused

• the state to contained references to opentofu's registry instead, and
• the terraform provider to unpak under a registry.opentofu.org directory instead of the expected registry.terraform.io directory.

With this change we expect to have only references to registry.terraform.io unless otherwise specified by the brokerpak both in

• the state and
• directory structure

Checklist:

• [x] Have you added or updated tests to validate the changed functionality?
• [ ] Have you added Release Notes in the docs repositories?
• [x] Have you followed the Conventional Commits specification?

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/187390468

The labels on this github issue will be updated when the story is started.