Cannot run in windows wsl2

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

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

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

`[2026/01/28 00:01:53.978 +08:00] [FATAL] [terror.go:309] ["unexpected error"] [error="can't read memory.max from cgroup v2: open /sys/fs/cgroup/memory.max: no such file or directory"]`

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

The failure is reported at terror.go:309; first reproduce TiDB on Windows WSL2 and inspect the cgroup-v2 memory.max lookup there. Done means TiDB starts successfully in that environment without the fatal missing-file error; the issue does not name a test or expected fallback.

Written by the indexing model from the issue text.