htlcswitch/test_utils: bump fwdpkg gc timeout to 15s

This commit increases the fwdpkg garbage collection
interval to 15s, to mitigate the likelihood of it
interfering with our unit tests related to fwdpkgs.

htlcswitch/test_utils.go

@@ -877,7 +877,7 @@ func newThreeHopNetwork(t testing.TB, aliceChannel, firstBobChannel,
 
 	const (
 		batchTimeout        = 50 * time.Millisecond
-		fwdPkgTimeout       = 5 * time.Second
+		fwdPkgTimeout       = 15 * time.Second
 		minFeeUpdateTimeout = 30 * time.Minute
 		maxFeeUpdateTimeout = 40 * time.Minute
 	)