NEZ-1673 fix： logs图表导出报错

nezha-fronted/src/components/chart/chart/chartLog.vue

@@ -216,7 +216,7 @@ export default {
       const limit = this.operations.limit
       const descending = this.operations.descending
       const params = {
-        logql: this.expressions,
+        logql: this.chartInfo.elements.map(item => item.expression),
         start: this.$stringTimeParseToUnix(this.filterTime[0]),
         end: this.$stringTimeParseToUnix(this.filterTime[1]),
         direction: descending ? 'backward' : 'forward',

nezha-fronted/src/components/chart/panelChart.vue

@@ -196,10 +196,10 @@ export default {
                 query += '&format=1'
                 if (!params || params.descending) {
                   this.chartInfo.descending = true
-                  query += '&direction=forward'
+                  query += '&direction=backward'
                 } else {
                   this.chartInfo.descending = false
-                  query += '&direction=backward'
+                  query += '&direction=forward'
                 }
               }
               // if (isChartPie(this.chartInfo.type)) {