switch from `jaeger-client` to `opentelemetry`

The [jaeger-client](https://github.com/jaegertracing/jaeger-client-python) library has been deprecated, and security support is due to end in July 2022. The replacement is [opentelemetry](https://github.com/open-telemetry/opentelemetry-python).

This will require rewriting, or replacing, https://github.com/erikjohnston/rust-jaeger-python-client.