fix: isolate langfuse env vars

[lizradway]

Description

Fix tracer tests failing when developers have Langfuse environment variables set locally introduced in #1768

The is_langfuse property checks three env vars (OTEL_EXPORTER_OTLP_ENDPOINT, OTEL_EXPORTER_OTLP_TRACES_ENDPOINT, LANGFUSE_BASE_URL), but the moto_env test fixture only cleared the first one. When a developer has Langfuse configured locally, the remaining env vars leak into tests, causing is_langfuse to unexpectedly return True. This triggers extra span.set_attributes() calls that break assert_called_once_with assertions.

The fix adds monkeypatch.delenv calls for OTEL_EXPORTER_OTLP_TRACES_ENDPOINT and LANGFUSE_BASE_URL to the moto_env fixture, ensuring all three langfuse-related env vars are cleared for tests.

Related Issues

N/A

Documentation PR

N/A

Type of Change

Bug fix

Testing

How have you tested the change?

• I ran hatch run prepare
• Verified all 76 tracer tests pass with Langfuse env vars set locally

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[github-actions]

Assessment: Approve

Clean, focused bug fix that correctly clears all three environment variables checked by the is_langfuse property, ensuring developer local configurations don't leak into tests.

Review Summary

• Completeness: The fix covers all env vars checked by is_langfuse (OTEL_EXPORTER_OTLP_ENDPOINT, OTEL_EXPORTER_OTLP_TRACES_ENDPOINT, LANGFUSE_BASE_URL)
• Documentation: Not required for this test infrastructure fix

Nice minimal fix! 👍