[ML] Rename JobNodeLoadDetectorTests to match tested class (elastic#7…

…5370)

Tested class is `NodeLoadDetector` thus the test class name
should be `NodeLoadDetectorTests`.

x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/job/JobNodeLoadDetectorTests.java → x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/job/NodeLoadDetectorTests.java

@@ -34,7 +34,7 @@
 import static org.mockito.Mockito.when;
 
 // TODO: in 8.0.0 remove all instances of MAX_OPEN_JOBS_NODE_ATTR from this file
-public class JobNodeLoadDetectorTests extends ESTestCase {
+public class NodeLoadDetectorTests extends ESTestCase {
 
     // To simplify the logic in this class all jobs have the same memory requirement
     private static final ByteSizeValue JOB_MEMORY_REQUIREMENT = ByteSizeValue.ofMb(10);