Use correct metric type in OTLP exporter

[golisai]

Description:
Fix to report the correct metric types in the OTLP exporter. Currently Gauge is being reported as Sum.

Link to tracking Issue: None

Testing:
Checked using the otlp log exporter

Metric #0
Descriptor:
     -> Name: http.client.duration.average
     -> Description:
     -> Unit: us
     -> DataType: Gauge
NumberDataPoints #0
Data point attributes:
     -> source.process.name: Str(kubelite)
     -> source.resolution_type: Str(PROCESS)
     -> dest.container.name: Str(coredns)
     -> source.workload.name: Str(snap.microk8s.daemon-kubelite)
     -> dest.image_version: Str(1.10.1)
     -> dest.namespace.name: Str(kube-system)
     -> dest.process.name: Str(coredns)
     -> dest.resolution_type: Str(K8S_CONTAINER)
     -> dest.workload.name: Str(coredns)
     -> dest.workload.uid: Str(0485c36b-283e-496e-af47-1a69545cd887)
     -> source.namespace.name: Str((unknown))
StartTimestamp: 2024-01-17 22:32:57.823206508 +0000 UTC
Timestamp: 2024-01-17 22:33:27.823206508 +0000 UTC
Value: 0.000177

Documentation: None

[yonch]

lgtm 👍

[golisai]

Thanks. @yonch with this patch we have all the fixes we are targeting for our release. Can you please cut a release tag?

[yonch]

👍 v0.10.2 is in progress in Github Actions: https://github.com/open-telemetry/opentelemetry-network/actions/runs/7575777545

[golisai]

Thanks