Make the subnet B to use different AZ than subnet A

[naxxster]

There is no reason to use same AZ in two subnet.
To follow best practice, changed the AZ of subnet B.

Issue #, if available:
#43

Description of changes:
Changed the AZ of subnet B to different one than subnet A

Checklist

• 👋 I have run the unit tests, and all unit tests have passed.
• ⚠️ This pull request might incur a breaking change.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[beomseoklee]

@naxxster thanks for your contribution. We've considered this one as well, but it broke the solution update. However, I put this one into our backlog item so that we can consider this one again.

[beomseoklee]

@naxxster Thanks for your contribution, and I've merged your PR.
Make sure that the change only happens in the GitHub repository, so if you launch the solution with the latest template, it will still have a single AZ for VPC subnets.

Once we release a new version, the feature will be fully available.