tests/resource/aws_acm_certificate: Use internal implementation for TLS key/certificate
tests/resource/aws_acm_certificate: Use internal implementation for TLS key/certificate

Reference: https://github.com/terraform-providers/terraform-provider-aws/issues/10023

Output from acceptance testing:

```
--- PASS: TestAccAWSAcmCertificate_imported_IpAddress (14.99s)
--- PASS: TestAccAWSAcmCertificate_imported_DomainName (23.89s)
```

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