fix(测试跟踪): 缺陷导出自定义字段名称过长展示优化

--bug=1019765 --user=宋昌昌 【测试跟踪】缺陷管理-导出-自定义字段显示不全 https://www.tapd.cn/55049933/s/1301020

test-track/frontend/src/business/issue/IssueList.vue

@@ -568,4 +568,8 @@ export default {
 :deep(.el-table) {
   overflow: auto;
 }
+
+span.operate-button button {
+  margin-left: 10px;
+}
 </style>

test-track/frontend/src/business/issue/components/export/IssueExportFieldList.vue

@@ -3,8 +3,8 @@
     <el-row v-for="rowIndex in fieldRowCount" :key="rowIndex">
     <span v-for="(item, index) in fields"
           :key="item.id">
-      <el-col :span="6"
+      <el-tooltip :content="item.name" :disabled="item.name.length < 6">
-              v-if="Math.floor(index / colCountEachRow) === rowIndex - 1">
+        <el-col :span="6" v-if="Math.floor(index / colCountEachRow) === rowIndex - 1">
           <el-checkbox
             v-model="item.enable"
             :disabled="item.disabled"
@@ -12,6 +12,7 @@
             {{ item.name }}
           </el-checkbox>
         </el-col>
+      </el-tooltip>
     </span>
     </el-row>
   </div>
@@ -46,4 +47,13 @@ export default {
 .el-row {
   margin-bottom: 10px;
 }
+
+:deep(.el-checkbox .el-checkbox__label) {
+  overflow: hidden;
+  white-space: nowrap;
+  text-overflow: ellipsis;
+  max-width: 100px;
+  position: relative;
+  top: 5px;
+}
 </style>