Jira: make issue links title compact

Problem abstract

The current JIRA remote links titles are too long, as JIRA UI truncates the titles, it's troublesome to distinguish the links.

What does this MR do?

This removes "GitLab: mentioned on"

1. because GitLab identify is presented already with gitlab icon
2. link type "mentioned on" is identified with relation key

See Platform Docs:

• https://developer.atlassian.com/server/jira/platform/using-fields-in-remote-issue-links/#remote-confluence-examples

How it will look

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer