Merge branch 'issue-boards-new-list-stop-closing' into 'master'

Create new list dropdown stays open after new list

## What does this MR do?

After creating a new list, the dropdown stays open until the user closes the dropdown themselves.

## Screenshots (if relevant)

![keep-open](/uploads/06580dd552647b1a9e5fabc2c978148b/keep-open.gif)

## What are the relevant issue numbers?

Closes #22852

See merge request !6742

CHANGELOG.md

@@ -18,6 +18,7 @@ Please view this file on the master branch, on stable branches it's out of date.
   - Refactor less readable existance checking code from CoffeeScript !6289 (jlogandavison)
   - Simpler arguments passed to named_route on toggle_award_url helper method
   - Fix typo in framework css class. !7086 (Daniel Voogsgerd)
+  - New issue board list dropdown stays open after adding a new list
   - Fix: Backup restore doesn't clear cache
   - API: Fix project deploy keys 400 and 500 errors when adding an existing key. !6784 (Joshua Welsh)
   - Replace jquery.cookie plugin with js.cookie !7085

app/assets/javascripts/boards/components/new_list_dropdown.js.es6

@@ -33,6 +33,7 @@ $(() => {
 			},
 			filterable: true,
       selectable: true,
+      multiSelect: true,
       clicked (label, $el, e) {
         e.preventDefault();

spec/features/boards/boards_spec.rb

@@ -347,6 +347,19 @@ describe 'Issue Boards', feature: true, js: true do
           expect(page).to have_selector('.board', count: 5)
         end
+        it 'keeps dropdown open after adding new list' do
+          click_button 'Create new list'
+          wait_for_ajax
+
+          page.within('.dropdown-menu-issues-board-new') do
+            click_link done.title
+          end
+
+          wait_for_vue_resource
+
+          expect(find('.issue-boards-search')).to have_selector('.open')
+        end
+
         it 'moves issues from backlog into new list' do
           wait_for_board_cards(1, 6)