Add a smoke test verifying that the prometheus metrics exporter works

**Is your feature request related to a problem? Please describe.**
We don't have any smoke tests that verify that the prometheus metrics are properly exported.

**Additional context**
https://github.com/open-telemetry/opentelemetry-java-instrumentation/pull/4515
https://github.com/open-telemetry/opentelemetry-java-instrumentation/issues/4460
