Returns a test run. Use the id you got when you started the run, without
startTime.

• stage is where the run is in its lifecycle, for example NOT_STARTED,
  RUNNING, COMPLETED or CANCELLED.
• status is the outcome, for example PASSED, FAILED or INCOMPLETE.

A 200 response does not mean the tests passed. Treat a run as passed only
when stage is COMPLETED, status is PASSED and numberOfTestCases is
greater than 0.

With startTime, {id} is read as a scheduler ID and the response
describes that future occurrence.

Requires the TestRun:Read permission.