Changes

ci(prow,tekton,pipelines): add pingcap-inc active-active triggers and revert ticdc env OCI host change (#4291)

## Summary
- Add active-active branch CI triggers for `pingcap-inc/tidb` and
`pingcap-inc/ticdc`:
  - update release presubmit configs in Prow
- add Tekton `git-push` triggers under
`tekton/v1/triggers/triggers/env-gcp/pingcap-inc/{tidb,ticdc}`
  - register new trigger files in env-gcp `kustomization.yaml`
- Update 7 `pipelines/pingcap/ticdc/latest/*` integration pipelines to
revert PR changes in `environment.OCI_ARTIFACT_HOST`:
- restore `environment` host to fixed public hub value
(`us-docker.pkg.dev/pingcap-testing-account/hub`)
- keep per-step `OCI_ARTIFACT_HOST=...` override for TiDB download, so
`pingcap-inc` still uses internal mirror for TiDB artifacts

## Changed Files
- `pipelines/pingcap/ticdc/latest/*` (7 pipeline files)
- `prow-jobs/pingcap-inc/tidb/release-presubmits.yaml`
- `prow-jobs/pingcap-inc/ticdc/release-presubmits.yaml`
- `tekton/v1/triggers/triggers/env-gcp/kustomization.yaml`
- `tekton/v1/triggers/triggers/env-gcp/pingcap-inc/tidb/git-push.yaml`
- `tekton/v1/triggers/triggers/env-gcp/pingcap-inc/ticdc/git-push.yaml`

## Notes
- This PR now reflects the current branch state after reverting
unrelated `tidb` release-8.5 pipeline changes.

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: wuhuizuo <2574558+wuhuizuo@users.noreply.github.com>
Co-authored-by: wuhuizuo <wuhuizuo@126.com>
 (commit: 824b228)