Merge branch '18707-label-tooltips-dont-dissapear-firefox' into 'master'

Hide tooltip manually

## What does this MR do?
Fixes an issue with tooltips not dissapearing  on Firefox after toggling label priority

## What are the relevant issue numbers?
Closes #18707

## Screenshots (if relevant)

**Test on Firefox**

![label-firefox](/uploads/09ed05f81b9861d666e5d9ad805fb501/label-firefox.gif)
## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- [ ] Tests
  - [ ] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4715

app/assets/javascripts/LabelManager.js.coffee

@@ -27,6 +27,11 @@ class @LabelManager
     $btn = $(e.currentTarget)
     $label = $("##{$btn.data('domId')}")
     action = if $btn.parents('.js-prioritized-labels').length then 'remove' else 'add'
+
+    # Make sure tooltip will hide
+    $tooltip = $ "##{$btn.find('.has-tooltip:visible').attr('aria-describedby')}"
+    $tooltip.tooltip 'destroy'
+
     _this.toggleLabelPriority($label, action)
 
   toggleLabelPriority: ($label, action, persistState = true) ->