Migrate `wasp new:ai` tests to ephemeral tests

[sodic]

We started automatically testing Wasp AI with #3415. This is all there is to it:

wasp/.github/workflows/ci-wasp-ai-test.yaml

Line 30 in 24b4b44

- name: Run `wasp new:ai` smoke test

@FranjoMindek is creating an ephemeral testing platform in #3465. Once that's done, we should integrte wasp ai:new tests in there and remove the special case from the CI.