[hotfix]groovy class cache leak (#9716)

* groovy class cache needs to be clean up;
* downside is template cache reuse is not possible. but luckily we don't reuse template that often.

Co-authored-by: Rong Rong <[email protected]>
Co-authored-by: Xiaotian (Jackie) Jiang <[email protected]>

pinot-spi/src/main/java/org/apache/pinot/spi/utils/GroovyTemplateUtils.java

@@ -18,6 +18,7 @@
  */
 package org.apache.pinot.spi.utils;
 
+import groovy.lang.GroovyShell;
 import groovy.text.SimpleTemplateEngine;
 import java.io.IOException;
 import java.time.Instant;
@@ -33,15 +34,18 @@ public class GroovyTemplateUtils {
   private GroovyTemplateUtils() {
   }
 
-  private static final SimpleTemplateEngine GROOVY_TEMPLATE_ENGINE = new SimpleTemplateEngine();
+  private static final GroovyShell GROOVY_SHELL = new GroovyShell();
+  private static final SimpleTemplateEngine GROOVY_TEMPLATE_ENGINE = new SimpleTemplateEngine(GROOVY_SHELL);
   private static final DateTimeFormatter DATE_FORMAT =
       DateTimeFormatter.ofPattern("yyyy-MM-dd").withZone(ZoneOffset.UTC);
 
   public static String renderTemplate(String template, Map<String, Object> newContext)
       throws IOException, ClassNotFoundException {
     Map<String, Object> contextMap = getDefaultContextMap();
     contextMap.putAll(newContext);
-    return GROOVY_TEMPLATE_ENGINE.createTemplate(template).make(contextMap).toString();
+    String templateRendered = GROOVY_TEMPLATE_ENGINE.createTemplate(template).make(contextMap).toString();
+    GROOVY_SHELL.resetLoadedClasses();
+    return templateRendered;
   }
 
   /**