update version of prometheus and OTel SDK

[braydonk]

Description

This PR updates the version of Prometheus used by the Ops Agent; this is where we pull the structs for the Prometheus configuration (unrelated to the version of Prometheus used by the collector subagent).

Updates to the OTel SDK and Google Cloud Exporter were necessary for the module update to reconcile.

The following commands were used:

go get -u github.com/prometheus/prometheus@latest
go get -u go.opentelemetry.io/otel/sdk/metric@latest
go get -u github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/metric@latest

Then I had to adjust for the fact that the aggregation package has been removed from the SDK.

Related issue

How has this been tested?

It builds and all unit tests pass locally.

Checklist:

• Unit tests
  • Unit tests do not apply.
  • Unit tests have been added/modified and passed for this PR.
• Integration tests
  • Integration tests do not apply.
  • Integration tests have been added/modified and passed for this PR.
• Documentation
  • This PR introduces no user visible changes.
  • This PR introduces user visible changes and the corresponding documentation change has been made.
• Minor version bump
  • This PR introduces no new features.
  • This PR introduces new features, and there is a separate PR to bump the minor version since the last release already.
  • This PR bumps the version.

[jefferbrecht]

LGTM, test failures look unrelated