provider/google: Provide valid config in acctest

The changes to allow for testing ID-only refresh conflict with passing
in "" as Config for tests. In this case we instead construct a config
with a known-non-existent bucket name.

builtin/providers/google/resource_storage_bucket_test.go

@@ -117,7 +117,7 @@ func TestAccStorageForceDestroy(t *testing.T) {
 				),
 			},
 			resource.TestStep{
-				Config: "",
+				Config: testGoogleStorageBucketsReaderCustomAttributes("idontexist"),
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckCloudStorageBucketMissing(bucketName),
 				),