test: removing terraform tests

Tests as well as examples are a maintenance overhead.
Users of this module who want tests can implement their own by incorporating them into their own wrapper module.
In assertions, just refer to `module.module_name.aws_wafv2_rule` instead of `aws_wafv2_web_acl.this.rule`.

Author: benpriestman

README.md

@@ -33,15 +33,6 @@ A Terraform module that creates Web Application Firewall (WAFV2).
 
 - See [Example Codes](https://github.com/aws-ss/terraform-aws-wafv2/tree/main/examples) for full details.
 
-## Tests
-
-This module has unit tests.
-To run them, do:
-
-```shell
-terraform test
-```
-
 <!-- BEGIN_TF_DOCS -->
 ## Requirements