Edit OTel Collector dashboard to include Datadog Exporter and Datadog Connector metrics

[liustanley]

What does this PR do?

Adds two new groups to the OOTB OTel Collector metrics dashboard:

Datadog Exporter: Traffic Sent

Datadog Connector: Stats Sent

Motivation

These two groups offer more observability into our collector components and the metrics are generated by the trace agent.

Additional Notes

Review checklist (to be filled by reviewers)

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• [ ] Changelog entries must be created for modifications to shipped code
• [ ] Add the qa/skip-qa label if the PR doesn't need to be tested during QA.