tests/resource/aws_batch_compute_environment: Skip disabling already disabled compute environments in sweeper
tests/resource/aws_batch_compute_environment: Skip disabling already disabled compute environments in sweeper

Previous output from sweeper:

```
$ go test ./aws -v -sweep=us-west-2 -sweep-run=aws_batch_compute_environment -timeout 10h
...
2019/02/20 21:09:37 [INFO] Disabling Batch Compute Environment: tf_acc_test_8263634293510486727
2019/02/20 21:09:37 [DEBUG] Waiting for state to become: [VALID]
2019/02/20 21:09:37 [TRACE] Waiting 5s before next try
2019/02/20 21:09:42 [TRACE] Waiting 10s before next try
2019/02/20 21:09:52 [TRACE] Waiting 10s before next try
2019/02/20 21:10:03 [TRACE] Waiting 10s before next try
2019/02/20 21:10:13 [TRACE] Waiting 10s before next try
2019/02/20 21:10:23 [TRACE] Waiting 10s before next try
2019/02/20 21:10:33 [TRACE] Waiting 10s before next try
2019/02/20 21:10:44 [ERROR] Failed to disable Batch Compute Environment tf_acc_test_8263634293510486727: unexpected state 'INVALID', wanted target 'VALID'. last error: %!s(<nil>)
2019/02/20 21:10:44 [INFO] Disabling Batch Compute Environment: tf_acc_test_8020949733708243984
2019/02/20 21:10:44 [DEBUG] Waiting for state to become: [VALID]
2019/02/20 21:10:44 [TRACE] Waiting 5s before next try
2019/02/20 21:10:49 [TRACE] Waiting 10s before next try
2019/02/20 21:10:59 [TRACE] Waiting 10s before next try
2019/02/20 21:11:10 [TRACE] Waiting 10s before next try
2019/02/20 21:11:20 [TRACE] Waiting 10s before next try
2019/02/20 21:11:30 [TRACE] Waiting 10s before next try
2019/02/20 21:11:40 [TRACE] Waiting 10s before next try
2019/02/20 21:11:50 [ERROR] Failed to disable Batch Compute Environment tf_acc_test_8020949733708243984: unexpected state 'INVALID', wanted target 'VALID'. last error: %!s(<nil>)
...
```

Output from sweeper:

```
$ go test ./aws -v -sweep=us-west-2 -sweep-run=aws_batch_compute_environment -timeout 10h
...
2019/02/21 09:22:37 Sweeper Tests ran:
	- aws_batch_job_queue
	- aws_batch_compute_environment
```

Ninir/terraform-provider-aws,terraform-providers/terraform-provider-aws,terraform-providers/terraform-provider-aws,terraform-providers/terraform-provider-aws,terraform-providers/terraform-provider-aws,Ninir/terraform-provider-aws,Ninir/terraform-provider-aws,kjmkznr/terraform-provider-aws,kjmkznr/terraform-provider-aws,Ninir/terraform-provider-aws,kjmkznr/terraform-provider-aws,kjmkznr/terraform-provider-aws