优化在JobThread尝试30次后销毁任务时，并发插入到triggerQueue中任务会失败的场景

xxl-job-core/src/main/java/com/xxl/job/core/thread/JobThread.java

@@ -165,9 +165,11 @@ public class JobThread extends Thread{
 
 				} else {
 					if (idleTimes > 30) {
+						if(triggerQueue ==null||triggerQueue.size()==0) {
 							XxlJobExecutor.removeJobThread(jobId, "excutor idel times over limit.");
 						}
 					}
+				}
 			} catch (Throwable e) {
 				if (toStop) {
 					XxlJobLogger.log("<br>----------- JobThread toStop, stopReason:" + stopReason);