fix: duplicate mention notification (backport #2907)

[mergify]

Issue:
When a user reacts on a comment, the "on_update" hook is triggered which send a mention notification everytime a comment is updated i.e. whenever a person reacts on it.

Fix:
Dont sent mention notification when a user reacts to a comment

---

This is an automatic backport of pull request #2907 done by Mergify.

[mergify]

Cherry-pick of 67a753e has failed:

On branch mergify/bp/main-hotfix/pr-2907
Your branch is up to date with 'origin/main-hotfix'.

You are currently cherry-picking commit 67a753e5.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   desk/src/components/notifications/Notifications.vue

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   helpdesk/helpdesk/doctype/hd_ticket_comment/hd_ticket_comment.py

Cherry-pick of 07ea05a has failed:

On branch mergify/bp/main-hotfix/pr-2907
Your branch is ahead of 'origin/main-hotfix' by 1 commit.
  (use "git push" to publish your local commits)

You are currently cherry-picking commit 07ea05aa.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   helpdesk/helpdesk/doctype/hd_ticket_comment/hd_ticket_comment.py

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[RitvikSardana]

Depends on: #2812