tests/resource/aws_redshift_subnet_group: Implement sweeper and disappears test (#14828)
tests/resource/aws_redshift_subnet_group: Implement sweeper and disappears test (#14828)

Reference: https://github.com/terraform-providers/terraform-provider-aws/issues/13826
Reference: https://github.com/terraform-providers/terraform-provider-aws/issues/14574

Output from acceptance testing in AWS Commercial:

```
--- PASS: TestAccAWSRedshiftSubnetGroup_disappears (26.83s)
```

Output from acceptance testing in AWS GovCloud (US):

```
--- PASS: TestAccAWSRedshiftSubnetGroup_disappears (30.85s)
```

Output from sweeper in AWS Commercial (aws_redshift_cluster failures unrelated):

```
2020/08/25 10:13:32 [DEBUG] Running Sweepers for region (us-west-2):
2020/08/25 10:13:32 [DEBUG] Running Sweeper (aws_redshift_cluster) in region (us-west-2)
2020/08/25 10:13:34 [ERROR] Failed deleting Redshift cluster (tf-redshift-cluster-2045223997271387682): InvalidClusterState: Unable to delete the cluster tf-redshift-cluster-2045223997271387682. You can only delete clusters with ACTIVE, INCOMPATIBLE_NETWORK, INCOMPATIBLE_HSM, INCOMPATIBLE_RESTORE, INSUFFICIENT_CAPACITY, or HARDWARE_FAILURE lifecycle.
	status code: 400, request id: fda93346-21d9-46ae-b70a-637edb91777d
2020/08/25 10:13:34 [ERROR] Failed deleting Redshift cluster (tf-redshift-cluster-8644196052749068490): InvalidClusterState: Unable to delete the cluster tf-redshift-cluster-8644196052749068490. You can only delete clusters with ACTIVE, INCOMPATIBLE_NETWORK, INCOMPATIBLE_HSM, INCOMPATIBLE_RESTORE, INSUFFICIENT_CAPACITY, or HARDWARE_FAILURE lifecycle.
	status code: 400, request id: 980f1a92-52d8-41d0-b942-608b8a28d2b0
2020/08/25 10:13:34 [DEBUG] Running Sweeper (aws_redshift_subnet_group) in region (us-west-2)
2020/08/25 10:13:34 [INFO] Deleting Redshift Cluster Subnet Group: foo-1532990571165558666
2020/08/25 10:13:35 [INFO] Deleting Redshift Cluster Subnet Group: foo-2826273713642737832
2020/08/25 10:13:35 [INFO] Deleting Redshift Cluster Subnet Group: foo-2972341912917468064
2020/08/25 10:13:35 [INFO] Deleting Redshift Cluster Subnet Group: foo-548170896135551408
2020/08/25 10:13:36 [INFO] Deleting Redshift Cluster Subnet Group: foo-6210951272445705940
2020/08/25 10:13:36 [INFO] Deleting Redshift Cluster Subnet Group: foo-6650827170013194054
2020/08/25 10:13:37 [INFO] Deleting Redshift Cluster Subnet Group: foo-8947122441846412195
2020/08/25 10:13:37 [INFO] Deleting Redshift Cluster Subnet Group: tf-acc-test-1033431615102227004
2020/08/25 10:13:37 [INFO] Deleting Redshift Cluster Subnet Group: tf-acc-test-3356016725088449244
2020/08/25 10:13:38 [INFO] Deleting Redshift Cluster Subnet Group: tf-acc-test-366062263239024705
2020/08/25 10:13:38 [INFO] Deleting Redshift Cluster Subnet Group: tf-acc-test-4635827958397283374
2020/08/25 10:13:38 [INFO] Deleting Redshift Cluster Subnet Group: tf-redshift-subnet-group-1676492653723899859
2020/08/25 10:13:39 [INFO] Deleting Redshift Cluster Subnet Group: tf-redshift-subnet-group-1799088798996484452
2020/08/25 10:13:39 [INFO] Deleting Redshift Cluster Subnet Group: tf-redshift-subnet-group-3024108242023612112
2020/08/25 10:13:40 [INFO] Deleting Redshift Cluster Subnet Group: tf-redshift-subnet-group-3299406627706074951
2020/08/25 10:13:40 [INFO] Deleting Redshift Cluster Subnet Group: tf-redshift-subnet-group-5403800648237234931
2020/08/25 10:13:40 [INFO] Deleting Redshift Cluster Subnet Group: tf-redshift-subnet-group-625135235143178083
2020/08/25 10:13:41 [INFO] Deleting Redshift Cluster Subnet Group: tf-redshift-subnet-group-8306727858374757773
2020/08/25 10:13:41 [INFO] Deleting Redshift Cluster Subnet Group: tf-redshift-subnet-group-8365684838675699564
2020/08/25 10:13:41 Sweeper Tests ran successfully:
	- aws_redshift_cluster
	- aws_redshift_subnet_group
2020/08/25 10:13:41 [DEBUG] Running Sweepers for region (us-east-1):
2020/08/25 10:13:41 [DEBUG] Running Sweeper (aws_redshift_cluster) in region (us-east-1)
2020/08/25 10:13:42 [DEBUG] No Redshift clusters to sweep
2020/08/25 10:13:42 [DEBUG] Running Sweeper (aws_redshift_subnet_group) in region (us-east-1)
2020/08/25 10:13:42 Sweeper Tests ran successfully:
	- aws_redshift_subnet_group
	- aws_redshift_cluster
ok  	github.com/terraform-providers/terraform-provider-aws/aws	12.691s
```

Output from sweeper in AWS GovCloud (US) (aws_redshift_cluster failures unrelated):

```
2020/08/25 10:13:40 [DEBUG] Running Sweepers for region (us-gov-west-1):
2020/08/25 10:13:40 [DEBUG] Running Sweeper (aws_redshift_cluster) in region (us-gov-west-1)
2020/08/25 10:13:43 [ERROR] Failed deleting Redshift cluster (tf-redshift-cluster-1216426925668034673): InvalidClusterState: Unable to delete the cluster tf-redshift-cluster-1216426925668034673. You can only delete clusters with ACTIVE, INCOMPATIBLE_NETWORK, INCOMPATIBLE_HSM, INCOMPATIBLE_RESTORE, INSUFFICIENT_CAPACITY, or HARDWARE_FAILURE lifecycle.
	status code: 400, request id: 7b5f4c9e-959f-4e80-b01a-65f2cd066f71
2020/08/25 10:13:44 [ERROR] Failed deleting Redshift cluster (tf-redshift-cluster-219584981761242852): InvalidClusterState: There is an operation running on the Cluster. Please try to delete it at a later time.
	status code: 400, request id: 1c672709-d60b-43b0-aadd-1bdf6a5f4797
2020/08/25 10:13:44 [ERROR] Failed deleting Redshift cluster (tf-redshift-cluster-2558072814228197965): InvalidClusterState: There is an operation running on the Cluster. Please try to delete it at a later time.
	status code: 400, request id: cc46c761-1a19-4f3e-844d-6c5514eedbf1
2020/08/25 10:13:45 [ERROR] Failed deleting Redshift cluster (tf-redshift-cluster-6093122516016678979): InvalidClusterState: There is an operation running on the Cluster. Please try to delete it at a later time.
	status code: 400, request id: 24d63cb2-7635-4448-878e-2ccde8e03478
2020/08/25 10:13:45 [ERROR] Failed deleting Redshift cluster (tf-redshift-cluster-6534318059499305980): InvalidClusterState: There is an operation running on the Cluster. Please try to delete it at a later time.
	status code: 400, request id: 28e83e42-6e20-4366-9c86-25f04d5138ad
2020/08/25 10:13:46 [ERROR] Failed deleting Redshift cluster (tf-redshift-cluster-7172132402108784395): InvalidClusterState: There is an operation running on the Cluster. Please try to delete it at a later time.
	status code: 400, request id: 1f2cef04-05ef-42dc-bc2c-ce937032db61
2020/08/25 10:13:46 [ERROR] Failed deleting Redshift cluster (tf-redshift-cluster-8068671586261296151): InvalidClusterState: There is an operation running on the Cluster. Please try to delete it at a later time.
	status code: 400, request id: 7abeafb4-268c-4b4d-abae-91e1bcab4e01
2020/08/25 10:13:46 [DEBUG] Running Sweeper (aws_redshift_subnet_group) in region (us-gov-west-1)
2020/08/25 10:13:47 [INFO] Deleting Redshift Cluster Subnet Group: tf-acc-test-2418503084750398980
2020/08/25 10:13:48 [INFO] Deleting Redshift Cluster Subnet Group: tf-acc-test-2939943196500636311
2020/08/25 10:13:48 [INFO] Deleting Redshift Cluster Subnet Group: tf-acc-test-8506717930441343050
2020/08/25 10:13:49 Sweeper Tests ran successfully:
	- aws_redshift_cluster
	- aws_redshift_subnet_group
ok  	github.com/terraform-providers/terraform-provider-aws/aws	10.018s
```
terraform-providers/terraform-provider-aws,terraform-providers/terraform-provider-aws,terraform-providers/terraform-provider-aws,terraform-providers/terraform-provider-aws