data-source/aws_instance: Only call DescribeInstanceCreditSpecifications for T2 and T3 instance types
data-source/aws_instance: Only call DescribeInstanceCreditSpecifications for T2 and T3 instance types

References:
* https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeInstanceCreditSpecifications.html
* https://github.com/terraform-providers/terraform-provider-aws/issues/8055

Output from acceptance testing:

```
--- PASS: TestAccAWSInstanceDataSource_AzUserData (151.20s)
--- PASS: TestAccAWSInstanceDataSource_basic (97.18s)
--- PASS: TestAccAWSInstanceDataSource_blockDevices (101.25s)
--- PASS: TestAccAWSInstanceDataSource_creditSpecification (112.21s)
--- PASS: TestAccAWSInstanceDataSource_getPasswordData_falseToTrue (150.08s)
--- PASS: TestAccAWSInstanceDataSource_getPasswordData_trueToFalse (179.42s)
--- PASS: TestAccAWSInstanceDataSource_GetUserData (168.45s)
--- PASS: TestAccAWSInstanceDataSource_GetUserData_NoUserData (168.54s)
--- PASS: TestAccAWSInstanceDataSource_gp2IopsDevice (92.01s)
--- PASS: TestAccAWSInstanceDataSource_keyPair (78.48s)
--- PASS: TestAccAWSInstanceDataSource_PlacementGroup (98.86s)
--- PASS: TestAccAWSInstanceDataSource_privateIP (112.85s)
--- PASS: TestAccAWSInstanceDataSource_rootInstanceStore (86.97s)
--- PASS: TestAccAWSInstanceDataSource_SecurityGroups (260.40s)
--- PASS: TestAccAWSInstanceDataSource_tags (225.46s)
--- PASS: TestAccAWSInstanceDataSource_VPC (106.89s)
--- PASS: TestAccAWSInstanceDataSource_VPCSecurityGroups (99.98s)
```

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