Fixed add dashboard button id

Author: can-angun

plugins/dashboards/frontend/public/templates/dashboards-menu.html

@@ -2,7 +2,7 @@
     <div class="cly-vue-sidebar__header">
         <span class="cly-vue-sidebar__header-title" data-test-id="dashboard-menu-title">Dashboards</span>
         <span class="cly-vue-sidebar__header-button" v-if="canCreate">
-            <el-button type="success" size="small" @click="addDashboard" data-test-id="new-dashboard-button">
+            <el-button type="success" size="small" @click="addDashboard" data-test-id="add-dashboard-button">
                 <i class="ion-plus-circled"></i>
                 <span>New</span>
             </el-button>