Update to the assisted-service at commit
a40422bdea617f16cbdb724d53619ca74773be45.
This repo now contains multiple go modules, so we have to add overrides
for the internal references to the api and models modules.
* Replace terraform modules with github.com/hashicorp/terraform-exec.
* Remove all terraform providers.
* Remove all unneeded replaces.
* Tidy up the replace stanzas so that it is more clear why each replace is needed.
* Remove and re-create all indirect requires to clean up ones that are
no longer needed.
