Maximum number of range partition tables tested

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)
Reproduce by running this tool with the following command:
[CMD] go-ycsb load mysql -P workloads/oncall2929 -p mysql.host=* -p mysql.port=* -p threadcount=10 -p operationcount=2000 -p recordcount=0 -p initialpartitioncount=10000 -p autommit=0 -p databasename=partition360 -p tablecount=1 -p tablenameprefix=partition361_ -p droppartitioninterval=1000
- param: initialpartitioncount -> create 10000 partition
tablecount -> create # tables in db
other parameters are not important for this issue.
[tool] the tool is customized by this repo: https://github.com/yongpan0709/workloads, but the name 'go-ycsb' is reserved.

The cluster size:
TiDB * 2
TiKV * 4

```
CREATE TABLE `partition361_0` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT COMMENT '自增id',
`m_req_all` bigint(20) unsigned NOT NULL DEFAULT '0',
`text` varchar(2048) NOT NULL DEFAULT '',
`create_date` date NOT NULL DEFAULT '2000-01-01',
`aid` int(11) unsigned NOT NULL DEFAULT '0',
`atime` time NOT NULL DEFAULT '-01:00:00',
`create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`id`,`create_date`) /*T![clustered_index] NONCLUSTERED */,
UNIQUE KEY `unq_p` (`aid`,`atime`,`create_date`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
PARTITION BY RANGE COLUMNS(`create_date`)
```

Add 8192 partition tables to this partition361_0 【Maximum number of partitions. The maximum possible number of partitions for a given table not using the [NDB](https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster.html) storage engine is 8192. This number includes subpartitions. // https://github.com/pingcap/tidb/pull/20089】

`ALTER TABLE partition360.partition361_0 ADD PARTITION ( PARTITION p20350127 VALUES LESS THAN ('20350128') );
`

The only DDL operations for this cluster load are adding partitioned tables

### 2. What did you expect to see? (Required)
the cost of creating one partition < 1s under a strict limit on maximum number of partitions per table.

### 3. What did you see instead (Required)
Before hitting the limit, the cost is too large:
After 20 minutes, the time to execute a single DDL operation rose to 5 seconds

After a few hours, the single DDL execution time went up to 20 seconds, and after 7,000 executions it went up to 30 seconds

Flame map captured during the execution

### 4. What is your TiDB version? (Required)

```
v6.1.0-nightly
Edition: Community
Git Commit Hash: d3e076c2424c16329786a5433dfe1a27985eb113
Git Branch: heads/refs/tags/v6.1.0-nightly
UTC Build Time: 2022-04-13 23:03:34
GoVersion: go1.18
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false
```