[XPU][CI] Set pip index URL to Tsinghua mirror

[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!

[Copilot]

Pull request overview

This pull request configures the XPU CI pipeline to use Tsinghua University's PyPI mirror for faster package downloads in China-based CI environments.

• Adds pip configuration to use Tsinghua mirror as the global index URL
• Aims to improve package installation speed during XPU CI runs

[Copilot]

The pip config set global.index-url command permanently modifies the user's pip configuration file (~/.pip/pip.conf or ~/.config/pip/pip.conf). This can affect pip behavior outside of this CI script. Consider using the -i or --index-url flag directly in the pip install commands instead (e.g., python -m pip install -r requirements.txt -i https://pypi.tuna.tsinghua.edu.cn/simple) to scope the mirror usage to just this script without persisting global configuration changes.

Suggested change

	python -m pip config set global.index-url https://pypi.tuna.tsinghua.edu.cn/simple
	echo "pip requirements"
	python -m pip install -r requirements.txt
	# Use Tsinghua mirror for this install only
	echo "pip requirements"
	python -m pip install -r requirements.txt -i https://pypi.tuna.tsinghua.edu.cn/simple

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

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