fix(cloudformation): Don't fail Aurora instances for MultiAZ not being set

[enzowritescode]

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Description

Update CKV_AWS_157 to not fail Aurora instances for not having MultiAZ set since they do not support that property.

Fixes # ([4287])(https://github.com/bridgecrewio/checkov/issues/4287))

Checklist:

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