use more subtle datetime and title change for timeagoEl - use SCSS variable for timing on animation

app/assets/javascripts/issue_show/issue_title_description.vue

@@ -70,8 +70,6 @@ export default {
         this.tasks = this.apiData.task_status;
         this.descriptionFlag = { pre: true, pulse: false };
       }
-
-      return { noTitleChange, noDescriptionChange };
     },
     setTabTitle() {
       const currentTabTitleScope = this.titleEl.innerText.split('·');
@@ -109,9 +107,8 @@ export default {
     },
     updateEditedTimeAgo() {
       const toolTipTime = gl.utils.formatDate(this.apiData.updated_at);
-
       this.timeAgoEl.attr('datetime', this.apiData.updated_at);
-      this.timeAgoEl.attr('data-original-title', toolTipTime);
+      this.timeAgoEl.attr('title', toolTipTime).tooltip('fixTitle');
     },
   },
   computed: {

app/assets/stylesheets/pages/issues.scss

@@ -23,7 +23,7 @@
 }
 
 .issue-realtime-trigger-pulse {
-  transition: opacity 0.2s ease;
+  transition: opacity $fade-in-duration linear;
   opacity: 1;
 }