tests: fix TestLNTransport probabilistic failure
tests: fix TestLNTransport probabilistic failure

lucky CI run: https://github.com/spesmilo/electrum/runs/9273471816

pooler/electrum-ltc,pooler/electrum-ltc,spesmilo/electrum,pooler/electrum-ltc,spesmilo/electrum,pooler/electrum-ltc,spesmilo/electrum,spesmilo/electrum