'show stats_histograms' and 'admin checksum table' behaviour differ between tikv and unistore

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

I'm [testing paging protocol](https://github.com/pingcap/tidb/issues/35633) by running tidb UT with a real TiKV using this branch https://github.com/pingcap/tidb/pull/35647

```
tiup playground nightly --mode tikv-slim
cd executor
go test -run ^TestShowPartitionStats$ -with-tikv 127.0.0.1:2379
go test -run ^TestAdminChecksumOfPartitionedTable$ -with-tikv 127.0.0.1:2379
```

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

Test success

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

Test case `TestAdminChecksumOfPartitionedTable` and `TestShowPartitionStats` run success on unistore, but fail on tikv.
The behaviour is different on those two store engine.

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

master

```
commit 47a4f3a017768dda0b9a826451486c5539bc8427 (HEAD -> master, origin/master, origin/HEAD)
Author: Weizhen Wang
Date: Wed Jun 29 20:16:40 2022 +0800

*: enable unconvert (#35821)

ref pingcap/tidb#35345
```