[receiver/azuremonitor] Return concrete types

[nslaughter]

Component(s)

receiver/azuremonitor

Describe the issue you're reporting

This was raised by @michalpristas as a tangential comment to changes in #30224. I believe that the instance of this receiver's code more idiomatic approach of returning concrete types will make our code more maintainable - likely highlighting where we benefit from the layer of abstraction in interfaces and... where we don't.

[github-actions]

Pinging code owners:

• receiver/azuremonitor: @altuner @codeboten

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[crobert-1]

Sounds like a good idea to me, removing needs triage.

[github-actions]

This issue has been inactive for 60 days. It will be closed in 60 days if there is no activity. To ping code owners by adding a component label, see Adding Labels via Comments, or if you are unsure of which component this issue relates to, please ping @open-telemetry/collector-contrib-triagers. If this issue is still relevant, please ping the code owners or leave a comment explaining why it is still relevant. Otherwise, please close it.

Pinging code owners:

• receiver/azuremonitor: @nslaughter @codeboten

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[michalpristas]

This also sounds like a good first issue, do we have a label like that?

[led0nk]

@michalpristas
Just to make sure i understood the comment from PR #30224, we're talking about silently failing here:

opentelemetry-collector-contrib/receiver/azuremonitorreceiver/scraper.go

Lines 167 to 170 in 9396cd8

	s.armClientOptions = s.getArmClientOptions()
	s.clientResources = s.getArmClient()
	s.clientMetricsDefinitions = s.getMetricsDefinitionsClient()
	s.clientMetricsValues = s.GetMetricsValuesClient()

is this correct?