tests/resource/aws_sns_sms_preferences: Serialize testing and fix destroy function
tests/resource/aws_sns_sms_preferences: Serialize testing and fix destroy function

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