e2e storage: don't panic when server stops

Now that everything is connected to a per-test context, the gRPC server might
encounter an error before it gets shut down normally. We must not panic in that
case because it would kill the entire Ginkgo worker process. This is not even
an error, so just log it as info message.

test/e2e/storage/drivers/csi-test/driver/driver.go

@@ -157,7 +157,7 @@ func goServe(server *grpc.Server, wg *sync.WaitGroup, listener net.Listener, sta
 		started <- true
 		err := server.Serve(listener)
 		if err != nil {
-			panic(err.Error())
+			klog.Infof("gRPC server for CSI driver stopped: %v", err)
 		}
 	}()
 }