[unit test flake]: TestRbfCloseClosingNegotiationLocal fails

[guggero]

Occasional failure in unit tests (with cover, run here: https://github.com/lightningnetwork/lnd/actions/runs/13397366371/job/37423165732?pr=9521).

 --- FAIL: TestRbfCloseClosingNegotiationLocal (0.01s)
    --- FAIL: TestRbfCloseClosingNegotiationLocal/send_offer_rbf_iteration_loop (0.01s)
        rbf_coop_test.go:334: no dust field set, expected: no dust
        rbf_coop_test.go:334: no dust field set, expected: no dust
        rbf_coop_test.go:251: unexpected state transition: &{{0xc00027c900 0xc000249440}}
        rbf_coop_test.go:334: no dust field set, expected: no dust
        rbf_coop_test.go:334: no dust field set, expected: no dust

[Roasbeef]

Will look into it!

[KapilSareen]

Hey @guggero do you think this is a case of race-condition because of the t.Parallel()?
What are your opinions on removing it? It causes a slight delay in the total test run time:

$ go test ./lnwallet/chancloser/   # with t.Parallel()
ok      github.com/lightningnetwork/lnd/lnwallet/chancloser     0.290s
$ go test ./lnwallet/chancloser/  # t.Parallel() removed
ok      github.com/lightningnetwork/lnd/lnwallet/chancloser     0.314s

[yyforyongyu]

@KapilSareen What's its root cause?