Faster test: don’t retrieve all partnered channels
Retry failing requests that may work the 2nd time

Whenever YouTube returns 500, 503 or 400 (with Invalid Query body),
it is worth trying one more time after some seconds because most of
the times it works the second time. Why? Don’t ask me.
Merge branch 'retry-youtube-request-when-they-might-work-the-second-time'