single_node_set_new_hostname.js needs to call replSetReconfig with an assert.soonNoExcept

After the node changes state to REMOVED, it closes all of its connections. However, since there is a delay between the state transition and when connections are closed, we may find that the connection is closed when we arrive at the replSetReconfig command. This line needs to be wrapped in an assert.soonNoExcept to handle a potentially closed connection.