This is what the converter generates now:
"resource.attributes[\"service.name\"] == \"unknown_service\""

For better readability, the converter could use backticks:
`resource.attributes["service.name"] == "unknown_service"`

This would match better with the otel format:

processors:
  filter/drop_unwanted_telemetry:
    logs:
      log_record:
        - 'resource.attributes["service.name"] == "unknown_service"'