Keep in mind, that when the client closes the contract, they HAVE to leave feedback. But, if you close the contract they are not obligated to leave any feedback at all.
Sure, there's always a chance your client could give you bad feedback. But, and I can only speak from my own personal experience and the experience of other Upwork freelancers that I know and have talked to about this very matter. When I have closed a contract myself, it was normally because the client was unresponsive. They were happy with my work, but I chalked up their "unresponsiveness" to moving on with their busy professional life. In all of those contracts that I closed, the clients didn't bother to leave any feedback at all. Good luck, and let us know how things went for you.