[resource control] QPS of TPCC is unstable with 32 different resource group user

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)
plan/1683569
1. Create 32 users and a resource group, and attach rg to users.
2. Start 1 threads tpcc workload for each user.

### 2. What did you expect to see? (Required)

### 3. What did you see instead (Required)

### 4. What is your TiDB version? (Required)
./tidb-server -V
Release Version: v7.1.0-alpha
Edition: Community
Git Commit Hash: b67c0321c05adde025aac4b2915eb8ad9dea19dc
Git Branch: heads/refs/tags/v7.1.0-alpha
UTC Build Time: 2023-03-27 11:42:41
GoVersion: go1.20.2
Race Enabled: false
TiKV Min Version: 6.2.0-alpha
Check Table Before Drop: false
Store: unistore