OpenMetrics integration does not support special `target_info` metric

[sirianni]

Steps to reproduce the issue: Configure an openmetrics check against a target that exports target metadata using the target_info convention

# TYPE target info
# HELP target Target metadata
target_info{env="prod",hostname="myhost",datacenter="sdc",region="europe",owner="frontend"} 1

Describe the results you expected: I expected the tags within target_info to be attached on every other metric reported by this check and queryable in Datadog.

Describe the results you received: I only see the tags local to each metric present and queryable in Datadog.

I see a separate target_info metric in Datadog with the target-scoped tags.

Additional context One reason this feature is important as the OpenTelemetry specification mandates use of the target_info convention to report resource-scoped tags.

In SDK Prometheus (pull) exporters, resource attributes SHOULD be converted to a single target_info metric; otherwise, they MUST be dropped, and MUST NOT be attached as labels to other metric families. The target_info metric MUST be an info-typed metric whose labels MUST include the resource attributes, and MUST NOT include any other labels. There MUST be at most one target_info metric exposed on an SDK Prometheus endpoint.

[steveny91]

@sirianni Hello! Thanks for opening up this issue. I'll create a card internally to properly triage this feature. Can I also ask that you kindly create a support ticket as well to help us better keep track of it? Thanks in advance!