Found a data race in GCWorker

## Bug Report

Original report: https://ask.pingcap.com/t/data-race-found-in-version/474

Application environment: 3 TiKV nodes, 3 PD nodes, 2 TiDB nodes in a local cluster
PoC environment
TiDB version: 6.6.0 (commit b417ad0689795a265df9cdba22c40871f50b7e55)
Reproduction method: Brought the environment up and ran a simple bank account transaction workload, using the antithesis testing platform.

Problem: 3 Data Races observed:
First DATA RACE:

```
WARNING: DATA RACE
Read at 0x00c001e86958 by goroutine 9152:
github.com/pingcap/tidb/store/gcworker.(*GCWorker).resolveLocks()
/tidb/store/gcworker/gc_worker.go:1169 +0xb2
github.com/pingcap/tidb/store/gcworker.(*GCWorker).runGCJob()
/tidb/store/gcworker/gc_worker.go:767 +0x117
github.com/pingcap/tidb/store/gcworker.(*GCWorker).leaderTick.func1()
/tidb/store/gcworker/gc_worker.go:444 +0x6c

Previous write at 0x00c001e86958 by goroutine 1007:
github.com/pingcap/tidb/store/gcworker.(*GCWorker).checkLeader()
/tidb/store/gcworker/gc_worker.go:1920 +0x1cb
github.com/pingcap/tidb/store/gcworker.(*GCWorker).tick()
/tidb/store/gcworker/gc_worker.go:286 +0x64
github.com/pingcap/tidb/store/gcworker.(*GCWorker).start()
/tidb/store/gcworker/gc_worker.go:229 +0x659
github.com/pingcap/tidb/store/gcworker.(*GCWorker).Start.func1()
/tidb/store/gcworker/gc_worker.go:120 +0x64

Goroutine 9152 (running) created at:
github.com/pingcap/tidb/store/gcworker.(*GCWorker).leaderTick()
/tidb/store/gcworker/gc_worker.go:443 +0xb5a
github.com/pingcap/tidb/store/gcworker.(*GCWorker).tick()
/tidb/store/gcworker/gc_worker.go:293 +0x8f
github.com/pingcap/tidb/store/gcworker.(*GCWorker).start()
/tidb/store/gcworker/gc_worker.go:229 +0x659
github.com/pingcap/tidb/store/gcworker.(*GCWorker).Start.func1()
/tidb/store/gcworker/gc_worker.go:120 +0x64

Goroutine 1007 (running) created at:
github.com/pingcap/tidb/store/gcworker.(*GCWorker).Start()
/tidb/store/gcworker/gc_worker.go:120 +0x1f7
github.com/pingcap/tidb/store/driver.(*tikvStore).StartGCWorker()
/tidb/store/driver/tikv_driver.go:320 +0x98
github.com/pingcap/tidb/session.BootstrapSession()
/tidb/session/session.go:3467 +0x1aaa
github.com/pingcap/tidb/domain.(*Domain).rebuildSysVarCache()
/tidb/domain/sysvar_cache.go:147 +0x8d0
github.com/pingcap/tidb/sessionctx/variable.glob..func174()
/tidb/sessionctx/variable/sysvar.go:904 +0x5e
github.com/pingcap/tidb/sessionctx/variable.(*SysVar).ValidateWithRelaxedValidation()
/tidb/sessionctx/variable/variable.go:361 +0x1c7
github.com/pingcap/tidb/domain.(*Domain).rebuildSysVarCache()
/tidb/domain/sysvar_cache.go:146 +0x844
github.com/pingcap/tidb/domain.(*Domain).LoadSysVarCacheLoop()
/tidb/domain/domain.go:1448 +0xa8
github.com/pingcap/tidb/session.BootstrapSession()
/tidb/session/session.go:3350 +0x6d3
github.com/pingcap/tidb/domain.(*Domain).GetSessionCache()
/tidb/domain/sysvar_cache.go:62 +0x59
github.com/pingcap/tidb/session.(*session).loadCommonGlobalVariablesIfNeeded()
/tidb/session/session.go:3669 +0x104
github.com/pingcap/tidb/session.(*session).ExecuteStmt()
/tidb/session/session.go:2148 +0x145
github.com/pingcap/tidb/session.(*session).ExecuteInternal()
/tidb/session/session.go:1678 +0x31b
github.com/pingcap/tidb/domain.(*Domain).LoadPrivilegeLoop()
/tidb/domain/domain.go:1392 +0x130
github.com/pingcap/tidb/session.BootstrapSession()
/tidb/session/session.go:3343 +0x684
main.createStoreAndDomain()
/tidb/tidb-server/main.go:351 +0x304
main.main()
```

Data race detected.