Update integration test to cover CloudFormation output of NAT gateways

[rifelpet]

I noticed that #8051 didnt require updating an tests in order to pass which means that cloudformation output of NAT gateways weren't covered by our integration tests.

This adds that to the complex test case. this should cause #8051 to fail until it updates the expected CF as well :)

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[joshbranham]

@rifelpet just for my own understanding, is this copied from elsewhere or generated somehow?

[rifelpet]

It is generated. I think some of our tests have an env var you can set that will write the actual output to the expected files so you can make updates like this easily, but I don’t think these integration tests support that. I ended up just making these files empty, ran the tests, then copied the diff outputted by the failing test into the files.

[joshbranham]

/lgtm