Changes

prow(docs): migrate pull_verify presubmits from jenkins to kubernetes (#4537)

## Summary
- migrate `pingcap/docs` and `pingcap/docs-cn` `pull_verify` presubmits
to `agent: kubernetes`
- keep trigger/context/branches compatibility (`/test pull-verify`,
`context: pull-verify`)
- add explicit timeout, resources, amd64 affinity, and strict failure
handling

## Changed files
- `prow-jobs/pingcap/docs/docs-latest-presubmits.yaml`
- `prow-jobs/pingcap/docs/docs-cn-latest-presubmits.yaml`

## Notes
- commit: `b0d3b513`
- related Multica issue: FLA-107

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Signed-off-by: wuhuizuo <wuhuizuo@126.com>
 (commit: 6860e38)