create table bug in parallel

## Reproduce steps(demo docker is recommended)
```
./init.sh
openmldb/bin/openmldb --zk_cluster=127.0.0.1:2181 --zk_root_path=/openmldb --role=sql_client --cmd="create database db"
# exec in background, so it can be parallel
openmldb/bin/openmldb --zk_cluster=127.0.0.1:2181 --zk_root_path=/openmldb --role=sql_client --database=db --cmd="create table t1(c1 string, c2 int, c3 bigint, c4 float, c5 double, c6 timestamp, c7 date)" &
openmldb/bin/openmldb --zk_cluster=127.0.0.1:2181 --zk_root_path=/openmldb --role=sql_client --database=db --cmd="create table t1(c1 string, c2 int, c3 bigint, c4 float, c5 double, c6 timestamp, c7 date)" &
```
Here, we'll create two tables with the same name, and nameserver will miss the second table, only cache the first table in `db_table_info_`. (the newer table is not inserted, cuz we use std::map::insert)
But there're two tables, tid is different, you can check it in zookeeper by
```
/work/openmldb/zookeeper/bin/zkCli.sh -server 127.0.0.1:2181
get /openmldb/table/db_table_data/6
get /openmldb/table/db_table_data/7
```

You can check the only table in nameserver by
```
curl http://localhost:7527/NameServer/ShowTable -d'{"db":"db","table":"t1"}' | grep -Eo '"tid":[0-9]*'
```
For example, in my env, it shows `"tid":6`, so table tid 7 is missing.

The problem is that, you can drop table
```
openmldb/bin/openmldb --zk_cluster=127.0.0.1:2181 --zk_root_path=/openmldb --role=sql_client --database=db --cmd="drop table t1"
```
And the table 6 is deleted, you can't find it in nameserver:
```
curl http://localhost:7527/NameServer/ShowTable -d'{"db":"db","table":"t1"}'
{"code":0,"msg":"ok"}
```
But sql client will find the table 7 after refresh the catalog, cuz zookeeper has table 7.
```
openmldb/bin/openmldb --zk_cluster=127.0.0.1:2181 --zk_root_path=/openmldb --role=sql_client --database=db --cmd="show tables"
--------
Tables
--------
t1
--------

1 rows in set
```
Not the same table, but it looks like we can't drop the table.

## How to fix
We can restart the nameserver, it'll recover the missing table.

But we should avoid to create tables with the same name in parallel.