Can't use datasource in an ExpectError test

### Terraform Version

```
0.12.7 (SDK)
```

### Terraform Configuration Files

```hcl
data "google_compute_image" "my_image" {
family = "centos-7"
project = "gce-uefi-images"
}

resource "google_compute_instance_template" "foobar" {
name = "instancet-test-%s"
machine_type = "n1-standard-1"
can_ip_forward = false

disk {
source_image = "${data.google_compute_image.my_image.self_link}"
auto_delete = true
boot = true
}

disk {
source_image = "${data.google_compute_image.my_image.self_link}"
auto_delete = true
type = "SCRATCH"
disk_type = "local-ssd"
}

disk {
source_image = "${data.google_compute_image.my_image.self_link}"
auto_delete = true
type = "SCRATCH"
}

network_interface {
network = "default"
}
}
```

### Debug Output

https://gist.github.com/rileykarson/c1024b54a0ebff4166f13f34133c3a63

### Crash Output

N/A

### Expected Behavior

The test case should pass.

### Actual Behavior

```
--- FAIL: TestAccComputeInstanceTemplate_invalidDiskType (1.13s)
testing.go:630: Error destroying resource! WARNING: Dangling resources
may exist. The full state and error is shown below.

Error: errors during refresh: 1 error occurred:
* SCRATCH disks must have a disk_type of local-ssd

State:
```

### Steps to Reproduce

`TF_LOG=DEBUG make testacc TEST=./google TESTARGS='-run=TestAccComputeInstanceTemplate_invalidDiskType'`

Using a hardcoded value instead of a datasource, I don't encounter the error and the test passes.

### Additional Context

This test isn't merged yet, but is staged at https://github.com/GoogleCloudPlatform/magic-modules/pull/2282

### References

Possible related to https://github.com/hashicorp/terraform/issues/18948