tools/etcd-test-proxy: remove newline in "Fprintln"
Fix govet warnings with Go tip
```
tools/etcd-test-proxy/main.go:47: Fprintln arg list ends with redundant
newline
```
@@ -62,8 +62,7 @@ $ ./bin/etcd-test-proxy --help
$ ./bin/etcd-test-proxy --from localhost:23790 --to localhost:2379 --http-port 2378 --verbose
$ ETCDCTL_API=3 ./bin/etcdctl --endpoints localhost:2379 put foo bar
-$ ETCDCTL_API=3 ./bin/etcdctl --endpoints localhost:23790 put foo bar
-`)
+$ ETCDCTL_API=3 ./bin/etcdctl --endpoints localhost:23790 put foo bar`)
flag.PrintDefaults()
}
