Flaky tests due to api address collisions

[mstoykov]

This seems to happen because

k6/cmd/tests/test_state.go

Line 121 in cb3f41c

func getFreeBindAddr(tb testing.TB) string {

is used to get the address, but it gets an address, then closes it. And after that k6 uses it.

There is a not small chance that another test will ask for an address between the close and k6 using it and then it will not be free. In practice even another process on the OS can get that address.

Unfortunately quite a lot of tests do use the address, so we can't just remove it.

It might be nice if we can get it from k6 running (maybe logs) and then use it to communicate?
Maybe we should not set it for tests that don't need it?