Set OTEL_EXPORTER_OTLP_METRICS_ENDPOINT needed for Java agent

[dineshg13]

Fixes a part of #73

Changes

Please provide a brief description of the changes here.

1. Update javaagent jar to the latest version
2. Set OTEL_EXPORTER_OTLP_METRICS_ENDPOINT as required by java agent . The variables are listed here https://github.com/open-telemetry/opentelemetry-java/blob/main/sdk-extensions/autoconfigure/README.md#otlp-exporter-both-span-and-metric-exporters

Post this change , when we do docker compose up , we should see jvm metrics in prometheus

[puckpuck]

Should we be using the OTEL_EXPORTER_OTLP_ENDPOINT environment variable only? We only have a single collector endpoint for all OTLP data, and shouldn't need to use the TRACES and METRICS specific flavors.

[julianocosta89]

@puckpuck, I'd argue that if we keep _TRACES and _METRICS we are "showcasing" how to use env vars to configure those 2 signals, even though they are pointing to the same collector.

Personally I'd accept this PR.

[austinlparker]

I suppose explicit is better than implicit, although I wonder if there are other implications of using the separate env vars for configuration?

[dineshg13]

i agree with @julianocosta89 & @austinlparker . i like variables being explicit in demo application.

[austinlparker]

This was discussed at the SIG meeting and we'd like to use explicit variables for each signal.

[cartersocha]

@dineshg13 could you please update the changelog too