[bug]: failed test `TestInvoiceRegistry/FailPartialAMPPayment_KV`

Found in this [build](https://github.com/lightningnetwork/lnd/actions/runs/13497728150/job/37708702128),
```
--- FAIL: TestInvoiceRegistry (4.85s)
    --- FAIL: TestInvoiceRegistry/FailPartialAMPPayment_KV (5.01s)
        invoiceregistry_test.go:2333: timeout waiting for HTLC resolution
FAIL
FAIL	github.com/lightningnetwork/lnd/invoices	536.459s
FAIL
```