Delete temp jars in classfile tests sooner (elastic#93019)

This commit more aggressively deletes the temporary jar files produced
to test jar scanning for plugins. By deleting right after use, any
leaked file handles should cause the tests to fail on windows.

relates elastic#93005

Author: rjernst

libs/plugin-scanner/src/test/java/org/elasticsearch/plugin/scanner/ClassReadersTests.java

@@ -8,6 +8,7 @@
 
 package org.elasticsearch.plugin.scanner;
 
+import org.elasticsearch.core.IOUtils;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.test.compiler.InMemoryJavaCompiler;
 import org.elasticsearch.test.jar.JarUtils;
@@ -39,6 +40,9 @@ public void testModuleInfoIsNotReturnedAsAClassFromJar() throws IOException {
 
         List<ClassReader> classReaders = ClassReaders.ofPaths(Stream.of(jar));
         org.hamcrest.MatcherAssert.assertThat(classReaders, Matchers.empty());
+
+        // aggressively delete the jar dir, so that any leaked filed handles fail this specific test on windows
+        IOUtils.rm(tmp);
     }
 
     public void testTwoClassesInAStreamFromJar() throws IOException {
@@ -57,6 +61,9 @@ public class B {}
         List<ClassReader> classReaders = ClassReaders.ofPaths(Stream.of(jar));
         List<String> collect = classReaders.stream().map(cr -> cr.getClassName()).collect(Collectors.toList());
         org.hamcrest.MatcherAssert.assertThat(collect, Matchers.containsInAnyOrder("p/A", "p/B"));
+
+        // aggressively delete the jar dir, so that any leaked filed handles fail this specific test on windows
+        IOUtils.rm(tmp);
     }
 
     public void testStreamOfJarsAndIndividualClasses() throws IOException {

libs/plugin-scanner/src/test/java/org/elasticsearch/plugin/scanner/NamedComponentScannerTests.java

@@ -8,6 +8,7 @@
 
 package org.elasticsearch.plugin.scanner;
 
+import org.elasticsearch.core.IOUtils;
 import org.elasticsearch.plugin.scanner.test_model.ExtensibleClass;
 import org.elasticsearch.plugin.scanner.test_model.ExtensibleInterface;
 import org.elasticsearch.plugin.scanner.test_model.TestNamedComponent;
@@ -100,6 +101,9 @@ public class B implements ExtensibleInterface{}
                 )
             )
         );
+
+        // aggressively delete the jar dir, so that any leaked filed handles fail this specific test on windows
+        IOUtils.rm(tmp);
     }
 
     public void testNamedComponentsCanExtednCommonSuperClass() throws IOException {
@@ -174,6 +178,9 @@ public class B implements CustomExtensibleInterface{}
                 )
             )
         );
+
+        // aggressively delete the jar dir, so that any leaked filed handles fail this specific test on windows
+        IOUtils.rm(tmp);
     }
 
     public void testWriteToFile() throws IOException {