goleak github.com/cockroachdb/pebble/vfs.(*diskHealthCheckingFile).startTicker

## 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)

```
--- PASS: TestPiTRCreateMultiColsIndex (8.06s)

PASS

coverage: 82.8% of statements

goleak: Errors on successful test run: found unexpected goroutines:

[Goroutine 2456813 in state select, with github.com/cockroachdb/pebble/vfs.(*diskHealthCheckingFile).startTicker.func1 on top of the stack:

goroutine 2456813 [select]:

github.com/cockroachdb/pebble/vfs.(*diskHealthCheckingFile).startTicker.func1()

external/com_github_cockroachdb_pebble/vfs/disk_health.go:63 +0xcb

created by github.com/cockroachdb/pebble/vfs.(*diskHealthCheckingFile).startTicker in goroutine 2456695

external/com_github_cockroachdb_pebble/vfs/disk_health.go:58 +0x58

]

```

https://do.pingcap.net/jenkins/blue/organizations/jenkins/pingcap%2Ftidb%2Fghpr_check2/detail/ghpr_check2/30788/pipeline

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