Expand e2e test coverage to include generating amplify_outputs doesn't break with new version

[Amplifiyer]

Description

we should expand this amplify_outputs test to cover programmatic read of outputs.

It would prevent us from launching breaking backwards incompatible changes. (See example here where we assert that old version can be read by new).

Reference PR that brought this to attention: https://github.com/aws-amplify/amplify-backend/pull/1917 and issue https://github.com/aws-amplify/amplify-backend/issues/1914