Remove redundant q.reset() calls and unused import

[hristog]

As per the QuantumDevice interface, the qubit reset() operation already takes place upon exiting from the using_device context manager, and this PR proposes removal of a couple of places where an explicit q.reset() is called immediately prior to exiting from the using_device context manager.

This PR supposes that the proposed-for-removal q.reset() lines weren't introduced explicitly with the intention of emphasizing that the operation would take place in a non-simulated context (as I suspect the case might have been here; if not - I would be happy to update this PR and remove that explicit q.reset() as well).

Thanks for reviewing this PR!