server: Use default logging configuration instead of zap production one

This fixes problem where logs json changes format of timestamp.

etcdutl/etcdutl/common.go

@@ -15,13 +15,14 @@
 package etcdutl
 
 import (
+	"go.etcd.io/etcd/client/pkg/v3/logutil"
 	"go.etcd.io/etcd/pkg/v3/cobrautl"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
 )
 
 func GetLogger() *zap.Logger {
-	config := zap.NewProductionConfig()
+	config := logutil.DefaultZapLoggerConfig
 	config.Encoding = "console"
 	config.EncoderConfig.EncodeTime = zapcore.RFC3339TimeEncoder
 	lg, err := config.Build()

etcdutl/snapshot/v3_snapshot.go

@@ -69,9 +69,6 @@ type Manager interface {
 
 // NewV3 returns a new snapshot Manager for v3.x snapshot.
 func NewV3(lg *zap.Logger) Manager {
-	if lg == nil {
-		lg = zap.NewExample()
-	}
 	return &v3Manager{lg: lg}
 }