build: onboard dependency installs to CFS

[fabiocav]

Description

Onboards repository-owned dependency installs to Central Feed Service (CFS):

• authenticates all Azure Pipelines Python jobs to public/upstream-public as the sole pip index and routes uv through UV_DEFAULT_INDEX
• maps NuGet exclusively to the CFS upstream feed, authenticates restore jobs, and copies the source config into detached webhost/extension build trees
• routes the repository-owned GitHub Actions global npm install through the CFS registry
• removes obsolete public/internal feed-selection parameters and generated legacy NuGet sources

Validation:

• parsed all checked-in YAML and changed JSON; compiled changed Python
• downloaded the complete Python 3.13 worker dependency graph (12 distributions) through CFS with an empty cache
• restored Newtonsoft.Json through CFS with an empty NuGet global-packages directory and paths containing spaces
• resolved azure-functions-core-tools@3 through the CFS npm registry
• verified all 16 PipAuthenticate@1 surfaces use onlyAddExtraIndex: false, and all five uv surfaces set UV_DEFAULT_INDEX

Caveat: cross-platform Python wheels are ingested independently by CFS. The full Windows/Python 3.13 graph resolved, while Linux, macOS, and ARM wheel availability remains covered by their pipeline jobs. Contributor/customer-local bootstraps remain unchanged because CFS PyPI authentication cannot be safely embedded outside Azure Pipelines.

Fixes # (none)

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Pull Request Checklist

Host-Worker Contract

• Does this PR impact the host-worker contract (e.g., gRPC messages, shared interfaces)?
  • If yes, have the changes been applied to:
    • azure_functions_worker (Python <= 3.12)
    • proxy_worker (Python >= 3.13)
  • If no, please explain why: No. This changes dependency-source configuration only.

Worker Execution Logic

• Does this PR affect worker execution logic (e.g., function invocation, bindings, lifecycle)?
  If yes, please answer the following:

No. This changes build and test dependency acquisition only.

Python Version Coverage

• Does this change apply to both Python <=3.12 and 3.13+?
• If yes, have the changes been made to:
  • azure_functions_worker (Python <= 3.12)
  • runtimes/v1 / runtimes/v2 (Python >= 3.13)
• If no, please explain why: N/A; no runtime execution logic changes.

Programming Model Compatibility (for Python 3.13+)

• Does this change apply to both:
  • V1 programming model (runtimes/v1)?
  • V2 programming model (runtimes/v2)?
• Explanation (if limited to one model): N/A; no programming-model behavior changes.

[azure-pipelines]

Azure Pipelines:
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[azure-pipelines]

Azure Pipelines:
There may be pipelines that require an authorized user to comment /azp run to run.