test: TestListenerTimeoutReadWrite non-deterministic test failure

https://github.com/tendermint/tendermint/pull/3575#issuecomment-484149537
```
=== RUN   TestListenerTimeoutReadWrite
--- FAIL: TestListenerTimeoutReadWrite (0.01s)
    socket_listeners_test.go:110: read tcp 127.0.0.1:38914->127.0.0.1:60772: i/o timeout
```