Remove redundant CHANGELOG.md entry after conflict resolution

Author: Blinkuu

CHANGELOG.md

@@ -15,8 +15,6 @@ release.
 
 - Add `MeasurementProcessor` to the Metrics SDK specification
    ([#4318](https://github.com/open-telemetry/opentelemetry-specification/pull/4318))
-- Clarify STDOUT exporter format is unspecified.
-   ([#4418](https://github.com/open-telemetry/opentelemetry-specification/pull/4418))
 
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