Re-enable AWS tags support

[iameskild]

Reference Issues or PRs

Closes #2095

What does this implement/fix?

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds a feature)
• Breaking change (fix or feature that would cause existing features not to work as expected)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Other (please describe):

Testing

• Did you test the pull request locally?
• Did you add new tests?

Any other comments?

[dcmcand]

@iameskild does this actually close #2095? It looks like it is part of #2095, but private subnet/vpc support is still needed.

[iameskild]

@dcmcand ah yes, there was already support for private/existing VPC and subnets, and I realized that it were just a small bug that was preventing it from working:

https://github.com/nebari-dev/nebari/pull/2096/files#diff-85a0aac851ba9454fb93be1ed93f3907ecbcea446f599a91424183dbce3cec75R447-R448

It should have been singular existing_security_group_id.