Report errors to log.Error channel in the spam exporter

[LukaszByczynski]

Component(s)

exporter/sapm

Describe the issue you're reporting

Currently, the spam exporter reports errors only to the debug channel. From an operational perspective, this setting is incorrect because if I want to monitor errors, I have to enable all debug logs, which is not my intention.

For instance, zipkin exporter logging errors to the correct log channel:

opentelemetry-collector-contrib/exporter/zipkinexporter/zipkin.go

Line 79 in e4d4bc9

return fmt.Errorf("failed to push trace data via Zipkin exporter: %w", err)

[github-actions]

Pinging code owners:

• exporter/sapm: @dmitryax @atoulme

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

[crobert-1]

Code owner approved PR resolving this issue, removing needs triage

[codeboten]

Fixed by #32430