Previously, the `backoff()` example did not work as intended. More
specifically, the `range(1, maxTries)` observable would complete
immediately after emitting the `maxTries`th value, causing the overall
observable to also complete. As a result, it would only make
`maxTries - 1` attempts to recover from an error. More importantly, the
outer observable would complete successfully instead of erroring.
This commit fixes the `backoff()` operator by ensuring it makes exactly
`maxTries` attempts to recover and it propagates the actual error to the
outer observable.
The test for this change is added in the next commit.
PR Close#38896
37297cfed7