bug6318: remove now-unused logger field from TestORCPerformanceCurve

The logger field became unused once the country-overview-based online fetch
was replaced with a fixed GER bulk fetch in setUp (its only use was the
"Trying to read country certificates for ..." info line). Remove the field
and the now-unused java.util.logging.Logger import so the workspace stays
warning-free.

Assisted-By: Claude Opus 4.8 (claude-opus-5-5)

java/com.sap.sailing.domain.test/src/com/sap/sailing/domain/orc/TestORCPerformanceCurve.java

@@ -12,7 +12,6 @@ import java.net.URL;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-import java.util.logging.Logger;
 
 import org.apache.commons.math.ArgumentOutsideDomainException;
 import org.apache.commons.math.FunctionEvaluationException;
@@ -47,8 +46,6 @@ import com.sap.sse.common.impl.NauticalMileDistance;
  */
 @ExtendWith(FailIfNoValidOrcCertificateRule.class)
 public class TestORCPerformanceCurve {
-    private static final Logger logger = Logger.getLogger(TestORCPerformanceCurve.class.getName());
-    
     private static ORCPerformanceCurveCourse alturaCourse;
     private static ORCCertificatesCollection importerLocal;
     private static ORCCertificatesCollection importerWithSpecificBins;