domain: use PutKVToEtcd in NotifyUpdateSysVarCache to avoid stuck by etcd operation (#61154)

close #60665

Author: qts0312

pkg/domain/domain.go

@@ -3075,8 +3075,7 @@ func (do *Domain) notifyUpdatePrivilege(event PrivilegeEvent) error {
 // synchronously so that the effect is immediate.
 func (do *Domain) NotifyUpdateSysVarCache(updateLocal bool) {
 	if do.etcdClient != nil {
-		row := do.etcdClient.KV
-		_, err := row.Put(context.Background(), sysVarCacheKey, "")
+		err := ddlutil.PutKVToEtcd(context.Background(), do.etcdClient, ddlutil.KeyOpDefaultRetryCnt, sysVarCacheKey, "")
 		if err != nil {
 			logutil.BgLogger().Warn("notify update sysvar cache failed", zap.Error(err))
 		}