fix(tidb): lock checkout cache for TiDB GCP Jenkins jobs (#4582)
### What changed
Use `prow.checkoutRefsWithCacheLock` for TiDB GCP Jenkins pipeline checkout caches in:
- `pingcap/tidb/latest/pull_integration_e2e_test_next_gen` - `pingcap/tidb/release-8.5/*` GCP Jenkins jobs
The change keeps the existing checkout parameters, including `withSubmodule = true` where it was already used.
### Why
Some GCP Jenkins jobs can fail while restoring/updating the Jenkins pipeline S3 cache with:
`AmazonS3Exception: A conflicting conditional operation is currently in progress against this resource`
This happens on shared git checkout cache keys when multiple builds access the same cache concurrently. `prow.checkoutRefsWithCacheLock` already wraps the git cache with a Jenkins lock, matching the pattern used by most latest TiDB jobs.