- Add _create_metric_stub_from_protobuf method to correctly parse protobuf metrics
- Add _extract_attributes_from_data_point helper method
- Change metric handling to use protobuf-specific parsing instead of OpenTelemetry native parsing
- Add missing typing import
- Add OTEL_METRIC_EXPORT_INTERVAL environment variable for test configuration
This fixes the CI failure where metrics were not being properly extracted from
protobuf data in server mode tests.
# What does this PR do?
Adds a test and a standardized way to build future tests out for
telemetry in llama stack.
Contributes to https://github.com/llamastack/llama-stack/issues/3806
## Test Plan
This is the test plan 😎