changed class name for no-alerts

public/app/plugins/panel/alertlist/module.html

 <div class="panel-alert-list" style="{{ctrl.contentHeight}}">
   <section class="card-section card-list-layout-list" ng-if="ctrl.panel.show === 'current'">
     <ol class="card-list">
-      <div class="no-alert" ng-style="{'height': + ctrl.panelHeight + 'px'}" ng-show="!ctrl.currentAlerts.length">
+      <div class="alert-list-no-alerts" ng-style="{'height': + ctrl.panelHeight + 'px'}" ng-show="!ctrl.currentAlerts.length">
         <p class="alert-list-title">
           No alerts in selected interval
         </p>

public/sass/pages/_alerting.scss

@@ -91,6 +91,13 @@
   align-items: flex-end;
 }
 
+.alert-list-no-alerts {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 100%;
+}
+
 .panel-has-alert {
   .panel-alert-icon:before {
     content: "\e611";
@@ -132,13 +139,6 @@
   }
 }
 
-.no-alert {
-  display: flex;
-  align-items: center;
-  justify-content: center;
-  width: 100%;
-}
-
 @keyframes alerting-panel {
   100% {
     opacity: 1;