multi: use chainntnfs.NewMiner for miners in unit tests

With the chainntnfs.NewMiner now being optimized for not creating
nodes with colliding ports, we use it in all unit tests that spin up
temporary miners.

lnwallet/test/test_interface.go

@@ -2120,11 +2120,9 @@ func testReorgWalletBalance(r *rpctest.Harness, w *lnwallet.LightningWallet,
 
 	// Now we cause a reorganization as follows.
 	// Step 1: create a new miner and start it.
-	r2, err := rpctest.New(r.ActiveNet, nil, []string{"--txindex"}, "")
-	require.NoError(t, err, "unable to create mining node")
-	err = r2.SetUp(false, 0)
-	require.NoError(t, err, "unable to set up mining node")
-	defer r2.TearDown()
+	r2 := chainntnfs.NewMiner(
+		t, r.ActiveNet, []string{"--txindex"}, false, 0,
+	)
 	newBalance, err := w.ConfirmedBalance(1, lnwallet.DefaultAccountName)
 	require.NoError(t, err, "unable to query for balance")
 	if origBalance != newBalance {
@@ -3103,14 +3101,9 @@ func TestLightningWallet(t *testing.T, targetBackEnd string) {
 	// dedicated miner to generate blocks, cause re-orgs, etc. We'll set
 	// up this node with a chain length of 125, so we have plenty of BTC
 	// to play around with.
-	miningNode, err := rpctest.New(
-		netParams, nil, []string{"--txindex"}, "",
+	miningNode := chainntnfs.NewMiner(
+		t, netParams, []string{"--txindex"}, true, 25,
 	)
-	require.NoError(t, err, "unable to create mining node")
-	defer miningNode.TearDown()
-	if err := miningNode.SetUp(true, 25); err != nil {
-		t.Fatalf("unable to set up mining node: %v", err)
-	}
 
 	// Next mine enough blocks in order for segwit and the CSV package
 	// soft-fork to activate on RegNet.