use daemon thread for scheduling in jmx-metrics BeanFinder (#11337)

Author: lizongwu

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/engine/BeanFinder.java

@@ -25,7 +25,13 @@ class BeanFinder {
 
   private final MetricRegistrar registrar;
   private MetricConfiguration conf;
-  private final ScheduledExecutorService exec = Executors.newSingleThreadScheduledExecutor();
+  private final ScheduledExecutorService exec =
+      Executors.newSingleThreadScheduledExecutor(
+          runnable -> {
+            Thread result = new Thread(runnable, "jmx_bean_finder");
+            result.setDaemon(true);
+            return result;
+          });
   private final long discoveryDelay;
   private final long maxDelay;
   private long delay = 1000; // number of milliseconds until first attempt to discover MBeans