Clean up remaining python 3.9 utilization

[scbedd]

Direct follow-up to #46508

As promised, cleaning up remaining matrix items.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR continues the cleanup of CI matrix configurations by removing remaining Python 3.9 references across multiple SDKs, updating matrix entries and coverage job identifiers accordingly.

Changes:

• Remove Python 3.9 from various platform-matrix.json / emulator matrix configurations.
• Rename matrix keys and test-agent identifiers that encoded 39 to 310, and move affected jobs to Python 3.10/3.11/3.12.

Show a summary per file

File	Description
sdk/planetarycomputer/platform-matrix.json	Removes 3.10/3.9 entries and updates coverage job from 3.9 to 3.10.
sdk/keyvault/azure-keyvault-keys/platform-matrix.json	Updates a remaining Python 3.9 job to Python 3.10.
sdk/identity/platform-matrix.json	Renames MSAL injected test config from 3.9 to 3.10 and updates version.
sdk/evaluation/platform-matrix.json	Removes 3.9 from matrix and updates coverage job naming/version to 3.10.
sdk/cosmos/live-platform-matrix.json	Renames Cosmos live test configs from 3.9 to 3.10 and updates version.
sdk/cosmos/cosmos-emulator-public-matrix.json	Replaces 3.9/3.10 emulator job names with 3.10/3.11 equivalents.
sdk/cosmos/cosmos-emulator-internal-matrix.json	Replaces 3.9/3.10 emulator job names with 3.10/3.11 equivalents.
sdk/communication/azure-communication-phonenumbers/phonenumbers-livetest-matrix.json	Removes remaining 3.9 coverage job, updates to 3.10, and updates the base Python versions list.
sdk/agentserver/platform-matrix.json	Removes 3.10/3.9 entries and updates coverage job from 3.9 to 3.10.

Copilot's findings

• Files reviewed: 9/9 changed files
• Comments generated: 3

[scbedd]

Going to bypass and merge. None of the failed checks are actually related to the change I made here. Addressed @kushagraThapar 's feedback RE making certain 3.10 sdist/wheel was covered.