opentelemetry-specification integration workflow: warnings detected

The `update-spec-integration-branch` workflow (for [`opentelemetry-specification`](https://github.com/open-telemetry/opentelemetry-specification)) reported the following warning(s): - Multiple integration branches found (v1.58.0, v1.57.0); using latest: v1.58.0. Older branches should be deleted. This issue was opened automatically; close it once the underlying condition is resolved. Workflow run: https://github.com/open-telemetry/opentelemetry.io/actions/runs/26284948236