htlcswitch: stop InvoiceRegistry in newMockRegistry cleanup

newMockRegistry started an InvoiceRegistry but never stopped it.
InvoiceRegistry internally starts two background goroutines —
invoiceEventLoop and the InvoiceExpiryWatcher mainLoop — that
run for the lifetime of the registry. Without a matching Stop()
call both goroutines leaked for every test that called
newMockRegistry, accumulating thousands of goroutines during
fuzzing.

Register a t.Cleanup to call registry.Stop() so both loops are
torn down when the test ends.

Author: MPins

htlcswitch/mock.go

@@ -1019,6 +1019,11 @@ func newMockRegistry(t testing.TB) *mockInvoiceRegistry {
 		},
 	)
 	registry.Start()
+	t.Cleanup(func() {
+		if err := registry.Stop(); err != nil {
+			t.Errorf("registry.Stop: %v", err)
+		}
+	})
 
 	return &mockInvoiceRegistry{
 		registry: registry,