fix：修改问题

1 chart 编辑页面 unit：选择不显示，修改后保存未起作用
2 chart legend由现在的纵向排列，改为和grafana一致横向排列换行
3 url,table,singleStat全屏窗口位置显示过于靠下
4 预览：宽度过宽则显示省略号

nezha-fronted/src/components/charts/chartPreview.vue

@@ -11,6 +11,15 @@
     .visible{
       visibility: visible;
     }
+    .chart-title {
+      display: flex;
+    }
+    .chart-title-text{
+      max-width:calc(100% - 175px);
+      text-overflow: ellipsis;
+      overflow: hidden;
+      white-space: nowrap;
+    }
 </style>
 <style>
   .char-url-preview html{
@@ -40,8 +49,8 @@
               <span class="panel-info-corner-inner"></span>
           </span>
       </el-popover>
-      <div slot="title">
-        <span class="nz-dialog-title">{{chart.title}}</span>
+      <div slot="title" class="chart-title">
+        <span class="nz-dialog-title chart-title-text">{{chart.title}}</span>
         <div class="float-right panel-calendar dialog-tool"  v-if="chart.type!=='url'">
 
           <time-picker ref="calendarPanel" class="nz-dashboard-picker" style="margin-top: -12px;" @change="dateChange"></time-picker>