feat: speed up the Docker build for dify-api for Chinese developers.

[erigo]

Checklist:

Important

Please review the checklist below before submitting your pull request.

• Please open an issue before creating a PR or link to an existing issue
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

Description

Fix #7622

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update, included: Dify Document
• Improvement, including but not limited to code refactoring, performance optimization, and UI/UX improvement
• Dependency upgrade

Testing Instructions

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test A
• Test B

[bowenliang123]

I suggest reverting this PR, for the reasons:

• it brings no feature or fix to the Dify users
• all the changes should be considered for the global Dify users across the world, not just for Chinese users'
• it implies a private vendor of Python Pypi's mirrors
• changing the mirror is easy and simple
• plenty of mirrors could be added for pip, yarn, node and many other Dify used package managers.

cc @crazywoola @laipz8200