Jira Issue Detail page: Jira users with username
What does this MR do?
Follow-up from !55221 (comment 520732927).
We are finishing the read-only version Jira Issue Detail page which is under the jira_issues_show_integration
feature flag. Now we are adding the Jira username/handle in the comments, see design: #322638[MVC_1_-_Jira_issue_comments.png] (comment 518991924).
Related to #322638 (closed)