Using default nodePort in tests in unreliable because it might already be occupied on CI

[pmalek]

Problem statement

Using a concrete, default nodePort:

kubernetes-testing-framework/pkg/clusters/addons/kong/addon.go

Line 540 in 238e12e

"--set", "proxy.http.nodePort=30080",

proves to be unreliable in tests, especially in CI since we don't have full control over the environment and sometimes the port can be already occupied e.g. https://github.com/Kong/kubernetes-testing-framework/actions/runs/5022546754/jobs/9006138317#step:8:144 which fails the test.

Proposed solution

Use something like github.com/phayes/freeport which allows finding a free port and use that in tests.

[programmer04]

The external library is not even needed for such a simple thing. Passing 0 as the port number instructs the kernel to give some random free port. It will work in this case too, btw. it's what the proposed library does under the hood (but the library ensures only that this port is free for the localhost address, which may be or not a problem). I suggest copying and adjusting a helper function for our use case