multi: use the "errors" package everywhere

Replace all usages of the "github.com/go-errors/errors" and
"github.com/pkg/errors" packages with the standard lib's "errors"
package. This ensures that error wrapping and `errors.Is` checks will
work as expected.

itest/lnd_zero_conf_test.go

@@ -1,12 +1,12 @@
 package itest
 
 import (
+	"errors"
 	"fmt"
 	"testing"
 	"time"
 
 	"github.com/btcsuite/btcd/btcutil"
-	"github.com/go-errors/errors"
 	"github.com/lightningnetwork/lnd/aliasmgr"
 	"github.com/lightningnetwork/lnd/chainreg"
 	"github.com/lightningnetwork/lnd/lnrpc"