fix: quic go-routine leak in tests

[dennis-tra]

By only enabling the TCP transport we won't leak quic-reuse goroutines in our tests: libp2p/go-libp2p#2514

Relates to: #34

We can't configure the leveldb timeout, so we're leaking one goroutine after each test for ~1s.

Then I found that there's another goroutine still dangling around after each test which could be closed with:

import (
	log "github.com/ipfs/go-log/writer"
)

func ... {
   log.WriterGroup.Close()
}