Changes

chore(pipeline) migrate tidb pull check and check2 to gcp and moidfy codecov upload (#4372)

## What changed

This PR migrates `release-8.5/pull_check` to GCP-ready runtime and
removes key dependencies on legacy IDC paths.

### 1) pull_check pod/runtime migration
- File: `pipelines/pingcap-inc/tidb/release-8.5/pod-pull_check.yaml`
- Changes:
  - Switch build image from `hub.pingcap.net/...` to GAR:
-
`us-docker.pkg.dev/pingcap-testing-account/internal/test/wangweizhen/tidb_image:go12320241009`
  - Set GOPROXY to GAR remote go proxy:
-
`https://us-go.pkg.dev/pingcap-testing-account/go-proxy-remote|https://proxy.golang.org,direct`
- Remove legacy PVC-based caches
(`gocache/gopathcache/bazel-out-lower/bazel-out-overlay`)
  - Use `ConfigMap bazel` instead of secret mount for `/data/`

verify in
https://prow.tidb.net/jenkins/job/pingcap-inc/job/tidb/job/release-8.5/job/pull_check2/9/console

https://prow.tidb.net/jenkins/job/pingcap-inc/job/tidb/job/release-8.5/job/pull_check/10/
 (commit: f93d839)