Python: added test to validate status set

[eavanvalkenburg]

Motivation and Context

Adds a test to validate that status is set to error for a execute_tool span.
Closes: #2217

Description

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
TOTAL	14965	2227	85%

report-only-changed-files is enabled. No files were changed during this commit :)

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
2039	129 💤	0 ❌	0 🔥	38.166s ⏱️

[Copilot]

Pull Request Overview

This PR replaces a complex mock-based test for exception handling with a simpler, more focused test that validates error status setting for function execution telemetry. The new test directly tests the ai_function decorator's error handling capabilities rather than mocking internal observability components.

Key Changes

• Removed unused imports (MagicMock, patch) that were only used in the old test
• Added ai_function import to support the new test
• Replaced test_agent_run_with_exception_handling with test_function_call_with_error_handling that tests actual function execution errors