[flaky test][receiver/opencensus] TestEnsureRecordedMetrics_zeroLengthSpansSender failing

[pjanotti]

Component(s)

receiver/opencensus

Describe the issue you're reporting

Looks like a race in the test, I couldn't repro it locally so likely it is low frequency. Detected at https://github.com/open-telemetry/opentelemetry-collector-contrib/actions/runs/13051122084/job/36411445776#step:8:351

=== FAIL: internal/octrace TestEnsureRecordedMetrics_zeroLengthSpansSender (0.10s)
    observability_test.go:82: 
        	Error Trace:	D:/a/opentelemetry-collector-contrib/opentelemetry-collector-contrib/receiver/opencensusreceiver/internal/octrace/observability_test.go:82
        	Error:      	Received unexpected error:
        	            	the following errors occurred:
        	            	 -  metric 'otelcol_receiver_accepted_spans' not found
        	            	 -  metric 'otelcol_receiver_refused_spans' not found
        	Test:       	TestEnsureRecordedMetrics_zeroLengthSpansSender

[github-actions]

Pinging code owners:

• receiver/opencensus: @open-telemetry/collector-approvers

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[crobert-1]

Added the name of the failing test to the title in an effort to make the issue easier to find in the future.