Fix deadlock in dd-task-scheduler (#10096)

Load JFR Handlers class early to prevent deadlock.

Author: rkennke

dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/Agent.java

@@ -924,6 +924,15 @@ private static synchronized void registerDeadlockDetectionEvent() {
 
   private static synchronized void registerSmapEntryEvent() {
     log.debug("Initializing smap entry scraping");
+
+    // Load JFR Handlers class early, if present (it has been moved and renamed in JDK23+).
+    // This prevents a deadlock. See https://bugs.openjdk.org/browse/JDK-8371889.
+    try {
+      AGENT_CLASSLOADER.loadClass("jdk.jfr.events.Handlers");
+    } catch (Exception e) {
+      // Ignore when the class is not found or anything else goes wrong.
+    }
+
     try {
       final Class<?> smapFactoryClass =
           AGENT_CLASSLOADER.loadClass(