#132: retry GitHub HTTP request when rate limited: does not sleep when
it should

We use ghStatus.SetSleepFn(sleepSpy) to spy on the requests to sleep
for the success case.

This causes, on purpose, all the test cases of
TestGitHubStatusSuccessMockAPI to fail, in the assert

    assert.DeepEqual(t, haveSleeps, tc.wantSleeps)

#132: retry GitHub HTTP request when rate limited: does not sleep when
it should

We use ghStatus.SetSleepFn(sleepSpy) to spy on the requests to sleep
for the failure case.

his causes, on purpose, all the test cases of
TestGitHubStatusFailureMockAPI to fail, in the assert

  assert.DeepEqual(t, haveSleeps, tc.wantSleeps)

Now that we have virtual sleep, we can use in the tests, as much as
possible, the same values of prod. This reduces the cognitive load to
compare tests and prod and convince oneself that it is the correct
behavior.

This is a good example of how they are more explicit and leave no doubt

Parameters rateLimitRemaining and rateLimitReset are not taken into
consideration when the HTTP status code is a transient error.

Since settings these values in the test cases gives the impression that
they influence the test, we remove them for clarity.

Test case "Any other error" covers the same logic of test case
"non transient error, stop at first attempt", so we remove it.