[Metax][CI] fix Metax ci bug

[plusNew001]

Motivation

💡 If this PR is a Cherry Pick, the PR title needs to follow the format by adding the [Cherry-Pick] label at the very beginning and appending the original PR ID at the end. For example, [Cherry-Pick][CI] Add check trigger and logic(#5191)

💡 如若此PR是Cherry Pick，PR标题需遵循格式，在最开始加上[Cherry-Pick]标签，以及最后面加上原PR ID，例如[Cherry-Pick][CI] Add check trigger and logic(#5191)

Modifications

Usage or Command

Accuracy Tests

Checklist

• Add at least a tag in the PR title.
  • Tag list: [[FDConfig],[APIServer],[Engine], [Scheduler], [PD Disaggregation], [Executor], [Graph Optimization], [Speculative Decoding], [RL], [Models], [Quantization], [Loader], [OP], [KVCache], [DataProcessor], [BugFix], [Docs], [CI], [Optimization], [Feature], [Benchmark], [Others], [XPU], [HPU], [GCU], [DCU], [Iluvatar], [Metax]]
  • You can add new tags based on the PR content, but the semantics must be clear.
• Format your code, run pre-commit before commit.
• Add unit tests. Please write the reason in this PR if no unit tests.
• Provide accuracy results.
• If the current PR is submitting to the release branch, make sure the PR has been submitted to the develop branch, then cherry-pick it to the release branch with the [Cherry-Pick] PR tag.

[paddle-bot]

Thanks for your contribution!

[plusNew001]

/skip all

[Copilot]

Pull request overview

该 PR 旨在修复 Metax 相关的 CI 触发问题，调整 CI_METAX 工作流中触发 Jenkins 的 job 所使用的 GitHub Actions Runner，以确保 PR 触发链路可用。

Changes:

• 将 ci_metax.yml 的 trigger-jenkins job 从指定 runner group 改为使用带标签的 self-hosted runner（[self-hosted, XPU-P800]）。
• 保持现有基于 pull_request_target 事件触发 Jenkins 的流程不变，仅调整运行环境选择。