perf(infrared-reading-meter-service): 优化获取有效电表号查询

- 在查询中只选择电表号字段，减少不必要的数据加载
- 移除了多余的注释，简化代码结构

infrared-reading-meter-service/src/main/java/com/zksy/infrared/service/impl/InfraredReadingMeterServiceImpl.java

@@ -415,9 +415,10 @@ public class InfraredReadingMeterServiceImpl extends ServiceImpl<InfraredReading
 
         // 获取所有有效的电表号（非空且有总电量记录）
         LambdaQueryWrapper<InfraredReadingMeter> allMeterQuery = new LambdaQueryWrapper<>();
-        allMeterQuery.isNotNull(InfraredReadingMeter::getElectricNumber)
+        allMeterQuery.select(InfraredReadingMeter::getElectricNumber) // 只查电表号
+                .isNotNull(InfraredReadingMeter::getElectricNumber)
                 .isNotNull(InfraredReadingMeter::getElectricEnergy)
-                .groupBy(InfraredReadingMeter::getElectricNumber); // 去重获取所有电表号
+                .groupBy(InfraredReadingMeter::getElectricNumber);
         List<String> allValidMeterNumbers = list(allMeterQuery).stream()
                 .map(InfraredReadingMeter::getElectricNumber)
                 .filter(Objects::nonNull)