fix(terraform): default value for CKV_AZURE_5

[fredgate]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Description

The check CKV_AZURE_5 should succeed if the role_based_access_control_enabled property is not set in resource azurerm_kubernetes_cluster as its default value is true.

Fixes #4227

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my feature, policy, or fix is effective and works
• New and existing tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[gruebel]

thanks 🍻