provider/gce: Fix whitespace in test fixture
provider/gce: Fix whitespace in test fixture

Mixture of hard and soft tabs, which isn't picked up by `go fmt` because
it's inside a string. Standardise on hard-tabs since that is what's used
in the rest of the code.

ubschmidt2/terraform-provider-google,nickithewatt/terraform-provider-google,drebes/terraform-provider-google,selmanj/terraform-provider-google,hashicorp/terraform-provider-google,hashicorp/terraform-provider-google,hashicorp/terraform-provider-google-beta,nickithewatt/terraform-provider-google,rosbo/terraform-provider-google,selmanj/terraform-provider-google,terraform-providers/terraform-provider-google,rosbo/terraform-provider-google,hashicorp/terraform-provider-google-beta,hashicorp/terraform-provider-google-beta,drebes/terraform-provider-google,nickithewatt/terraform-provider-google,terraform-providers/terraform-provider-google,selmanj/terraform-provider-google,ubschmidt2/terraform-provider-google,ubschmidt2/terraform-provider-google,ubschmidt2/terraform-provider-google,hashicorp/terraform-provider-google-beta,hashicorp/terraform-provider-google,rosbo/terraform-provider-google,terraform-providers/terraform-provider-google,rosbo/terraform-provider-google,terraform-providers/terraform-provider-google,drebes/terraform-provider-google,terraform-providers/terraform-provider-google,hashicorp/terraform-provider-google,drebes/terraform-provider-google