Changes

fileserver: migrate artifacts for pingcap/tiflow to OCI registry (#4265)

Removes all `fileserver.pingcap.net` references from `pingcap/tiflow` CI
pipelines and scripts, replacing binary artifact downloads with OCI
registry pulls via the existing `download_pingcap_oci_artifact.sh`
infrastructure. Also removes end-of-life `release-5.3`, `release-5.4`,
and `release-6.0` branch support.

## Script rewrites

- **`download_test_binaries_by_tag.sh`** — replaced sha1-lookup + wget
pattern with `download_pingcap_oci_artifact.sh` using version tag as OCI
tag
- **`ticdc_integration_test_download_dependency.sh`** — migrated
tidb/tikv/pd/tiflash + minio/ycsb/etcd/sync_diff_inspector to OCI
-
**`release-{6.1,6.5,6.5-fips}/ticdc_download_integration_test_binaries.sh`**
— replaced fileserver sha1 lookups with
`download_pingcap_oci_artifact.sh --tidb=$branch --tikv=$branch ...`;
`jq` now pulled from GitHub releases
-
**`release-*/dm_download_{integration,compatibility}_test_binaries.sh`**
— replaced fileserver tidb/tikv/pd/minio/tidb-tools downloads with OCI;
remaining `download.pingcap.com` URLs (GitHub, enterprise tools) left
untouched

## Pipeline migrations

- **`latest/ghpr_verify.groovy`** + **`merged_unit_test.groovy`** —
codecovcli wget now targets
`https://cli.codecov.io/v0.9.4/linux/codecovcli`
- **`latest/pull_syncdiff_integration_test.groovy`** +
**`release-9.0-beta/...`** — replaced
`component.fetchAndExtractArtifact(FILE_SERVER_URL, ...)` with OCI
downloads via `utils` container; removed deprecated
`tidb-enterprise-tools` download (loader/importer); added `utils`
container to both pod templates
- **All other tiflow pipelines (~127 files)** — `FILE_SERVER_URL =
'http://fileserver.pingcap.net'` → `OCI_ARTIFACT_HOST =
'hub-zot.pingcap.net/mirrors/hub'`

## OCI script extension

Added `--dumpling` flag to `download_pingcap_oci_artifact.sh`,
extracting the dumpling binary from the tidb OCI package
(`pingcap/tidb/package`):

```bash
download_pingcap_oci_artifact.sh \
  --tidb=master \
  --dumpling=master   # extracts dumpling from the same tidb OCI artifact
```

## EOL branch cleanup

Removed all `jobs/`, `pipelines/`, and `scripts/` for the end-of-life
`release-5.3` and `release-5.4` branches (42 files deleted), and all
`jobs/` and `pipelines/` for the end-of-life `release-6.0` branch (4
files deleted).

## Domain migration

Replaced all `download.pingcap.org` references with
`download.pingcap.com` across scripts, pipelines, Dockerfiles, and CI
steps (24 files updated), including legacy Jenkins pipelines,
tidb/tidb-tools pipelines, tiflow scripts, ops scripts, and Dockerfiles.

## Result

Zero `fileserver.pingcap.net` or `download.pingcap.org` references
remain in `jobs/`, `pipelines/`, or `scripts/` under `pingcap/tiflow`
(or anywhere else in the repository).

<!-- START COPILOT ORIGINAL PROMPT -->



<details>

<summary>Original prompt</summary>

> 
> ----
> 
> *This section details on the original issue you should resolve*
> 
> <issue_title>fileserver: migrate artifacts for
pingcap/tiflow</issue_title>
> <issue_description>Replace fileserver.pingcap.net usage for
pingcap/tiflow with OCI artifacts in a standard registry.
> 
> Acceptance criteria:
> - No fileserver.pingcap.net references in jobs/pipelines for
pingcap/tiflow
> - Artifacts pulled via OCI registry with documented paths
> </issue_description>
> 
> ## Comments on the Issue (you are @copilot in this section)
> 
> <comments>
> </comments>
> 


</details>



<!-- START COPILOT CODING AGENT SUFFIX -->

- Fixes PingCAP-QE/ci#4217

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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: Ti Chi Robot <ti-community-prow-bot@tidb.io>
Co-authored-by: wuhuizuo <wuhuizuo@126.com>
 (commit: ef91c40)