This PR tries to make API tests run fast, as an experiment to later apply
to all packages. Key changes include
- Swapping freeport for test/portal for port allocations
- Swappng some uses of WaitForResult with test/wait
- Turning on parallelism in api/testutil/slow.go
- Switching to custom public runner (32 vcpu)
There's also chunk of cleanup brought in for the ride
This is a followup to running tests in serial in CI.
Since the API package cannot import anything outside of api/,
copy the ci.Parallel function into api/internal/testutil, and
have api tests use that.
Seth Hoenig