Closes https://github.com/paritytech/parity-ethereum/issues/10687 `sleep()` is called from several places but when called from `disable()` or through the `setMode` RPC, we should ignore queue contents and go to sleep.
Closes https://github.com/paritytech/parity-ethereum/issues/10687 `sleep()` is called from several places but when called from `disable()` or through the `setMode` RPC, we should ignore queue contents and go to sleep.