tests: flaky TestHandleRemotePeerProtocolChanges

[guillaumemichel]

=== RUN   TestHandleRemotePeerProtocolChanges
    dht_test.go:1909: avg rt size: 1
    dht_test.go:1915: avg rt size: 1
    dht_test.go:1921: failed to reach well-formed routing tables after 10s
--- FAIL: TestHandleRemotePeerProtocolChanges (10.07s)

Run tests with race detector: Ubuntu go1.25

https://github.com/libp2p/go-libp2p-kad-dht/actions/runs/18891138785/job/53918792233?pr=1183#step:15:54