Fix initialization of DatasetUtilTests to avoid instance check if unsupported

Author: ChrisHegarty

x-pack/plugin/gpu/src/test/java/org/elasticsearch/xpack/gpu/codec/DatasetUtilsTests.java

@@ -22,18 +22,19 @@
 
 public class DatasetUtilsTests extends ESTestCase {
 
+    DatasetUtils datasetUtils;
+
     @Before
     public void setup() {  // TODO: abstract out setup in to common GPUTestcase
         assumeTrue("cuvs runtime only supported on 22 or greater, your JDK is " + Runtime.version(), Runtime.version().feature() >= 22);
         try (var resources = GPUVectorsFormat.cuVSResourcesOrNull(false)) {
             assumeTrue("cuvs not supported", resources != null);
         }
+        datasetUtils = DatasetUtils.getInstance();
     }
 
     static final ValueLayout.OfFloat JAVA_FLOAT_LE = ValueLayout.JAVA_FLOAT_UNALIGNED.withOrder(ByteOrder.LITTLE_ENDIAN);
 
-    final DatasetUtils datasetUtils = DatasetUtils.getInstance();
-
     public void testBasic() throws Exception {
         try (Directory dir = new MMapDirectory(createTempDir("testBasic"))) {
             int numVecs = randomIntBetween(1, 100);