Add support for globally disabling retries

[rouge8]

It would be very useful to disable retries (and sleeping and etc) in tests, similar to how it's supported by stamina: https://stamina.hynek.me/en/stable/tutorial.html#deactivating-retries-globally

[Olegt0rr]

aiocache is also available to be disabled via env var AIOCACHE_DISABLE

Looking for similar way for backoff

[fferegrino]

Woha, almost one year later. I am also interested on this.
Or any advice to disable the retries/backoff entirely for tests as I have a few that hang when testing the decorated functions.