terraform: Fix random VM image deployment errors

[henrirosten]

This is an attempt to fix the occasional errors that occur on clean deployments. An example terraform error from a deployment before the changes from this PR below:

│ Error: creating Blob "binary-cache.vhd" (Container "ghaf-infra-vm-images" / Account "imgreleaseeun"): creating storage blob
on Azure: while uploading source file "/nix/store/dvg2fqgxzd116zjhw9c5bbps96bzsfqi-azure-image/disk.vhd": writing page at 
offset 4455006208 for file "/nix/store/dvg2fqgxzd116zjhw9c5bbps96bzsfqi-azure-image/disk.vhd": 
blobs.Client#PutPageUpdate: Failure responding to request: StatusCode=403 -- Original Error: autorest/azure: Service returned 
an error. Status=403 Code="AuthenticationFailed" Message="Server failed to authenticate the request. Make sure the value of 
Authorization header is formed correctly including the signature.\n
RequestId:faafbdc5-e01e-0024-79b8-40a5e6000000\nTime:2024-11-27T10:37:11.7371065Z"
│
│   with module.binary_cache_image.azurerm_storage_blob.default,
│   on modules/azurerm-nix-vm-image/main.tf line 4, in resource "azurerm_storage_blob" "default":
│    4: resource "azurerm_storage_blob" "default" 

This change adds explicit dependencies, and also applies the workaround suggested in: hashicorp/terraform-provider-azurerm#15609.

With these changes, I was not able to reproduce the failure. Although, given the randomness of the error occurance, it's still possible this doesn't completely fix it.

[henrirosten]

Added azurerm_image.default dependency to data.external.nix_build

[henrirosten]

Rebased