refactor: remove useless initNetworkLog function

address @rudyfly’s [comment](AliyunContainerService#1445 (comment))

daemon/mgr/network.go

@@ -6,7 +6,6 @@ import (
 	"net"
 	"path"
 	"strings"
-	"time"
 
 	apitypes "github.com/alibaba/pouch/apis/types"
 	"github.com/alibaba/pouch/daemon/config"
@@ -69,8 +68,6 @@ func NewNetworkManager(cfg *config.Config, store *meta.Store, ctrMgr ContainerMg
 	cfg.NetworkConfg.MetaPath = path.Dir(store.BaseDir)
 	cfg.NetworkConfg.ExecRoot = network.DefaultExecRoot
 
-	initNetworkLog(cfg)
-
 	// get active sandboxes
 	ctrs, err := ctrMgr.List(context.Background(),
 		func(c *Container) bool {
@@ -536,18 +533,6 @@ func (nm *NetworkManager) getNetworkSandbox(id string) libnetwork.Sandbox {
 	return sb
 }
 
-func initNetworkLog(cfg *config.Config) {
-	if cfg.Debug {
-		logrus.SetLevel(logrus.DebugLevel)
-	}
-
-	formatter := &logrus.TextFormatter{
-		FullTimestamp:   true,
-		TimestampFormat: time.RFC3339Nano,
-	}
-	logrus.SetFormatter(formatter)
-}
-
 func endpointOptions(n libnetwork.Network, endpoint *types.Endpoint) ([]libnetwork.EndpointOption, error) {
 	var createOptions []libnetwork.EndpointOption
 	epConfig := endpoint.EndpointConfig