fix(scheduler): 修复固定频率调度类型的时间计算逻辑

- 修改了时间计算方式，使用 fromTime 而不是 triggerLastTime 作为基准
- 添加了秒级时间校准逻辑，确保时间精确到秒
- 移除了原有的条件判断分支，简化了时间计算流程
- 修复了时间戳毫秒部分不为0时的处理逻辑

xxl-job-admin/src/main/java/com/xxl/job/admin/scheduler/type/strategy/FixRateScheduleType.java

@@ -10,16 +10,17 @@ public class FixRateScheduleType extends ScheduleType {
 
     @Override
     public Date generateNextTriggerTime(XxlJobInfo jobInfo, Date fromTime) throws Exception {
+
         // generate next trigger time, fix rate delay
-        Date nextTriggerTime = new Date(jobInfo.getTriggerLastTime() + Long.parseLong(jobInfo.getScheduleConf()) * 1000L);
-        if (nextTriggerTime.after(fromTime)) {
-            // fix rate delay, after last-trigger-time
-            return nextTriggerTime;
-        } else {
-            // fix rate delay, after fromTime (clear ms, second +1)
-            fromTime = DateTool.setMilliseconds(DateTool.addSeconds(fromTime, 1), 0);
-            return new Date(fromTime.getTime() + Long.parseLong(jobInfo.getScheduleConf()) * 1000L);
+        Date nextTriggerTime = new Date(fromTime.getTime() + Long.parseLong(jobInfo.getScheduleConf()) * 1000L);
+
+        // assign second:
+        if (nextTriggerTime.getTime() % 1000 != 0) {
+            nextTriggerTime = DateTool.addSeconds(DateTool.setMilliseconds(nextTriggerTime, 0), 1);
         }
+
+        return nextTriggerTime;
+
     }
 
 }