Replace window.confirm with GlModal for noteable discussions

This commit replaces window.confirm dialog with
a GlModal when canceling a comment in a noteable discussionr.

Changelog: changed

app/assets/javascripts/notes/components/noteable_discussion.vue

@@ -5,6 +5,7 @@ import DraftNote from '~/batch_comments/components/draft_note.vue';
 import createFlash from '~/flash';
 import { clearDraft, getDiscussionReplyKey } from '~/lib/utils/autosave';
 import { isLoggedIn } from '~/lib/utils/common_utils';
+import { confirmAction } from '~/lib/utils/confirm_via_gl_modal/confirm_via_gl_modal';
 import { s__, __ } from '~/locale';
 import diffLineNoteFormMixin from '~/notes/mixins/diff_line_note_form';
 import TimelineEntryItem from '~/vue_shared/components/notes/timeline_entry_item.vue';
@@ -170,12 +171,13 @@ export default {
         this.expandDiscussion({ discussionId: this.discussion.id });
       }
     },
-    cancelReplyForm(shouldConfirm, isDirty) {
+    async cancelReplyForm(shouldConfirm, isDirty) {
       if (shouldConfirm && isDirty) {
         const msg = s__('Notes|Are you sure you want to cancel creating this comment?');
 
-        // eslint-disable-next-line no-alert
-        if (!window.confirm(msg)) {
+        const confirmed = await confirmAction(msg);
+
+        if (!confirmed) {
           return;
         }
       }

spec/features/issues/gfm_autocomplete_spec.rb

@@ -707,9 +707,10 @@ RSpec.describe 'GFM autocomplete', :js do
 
   def start_and_cancel_discussion
     fill_in('Reply to comment', with: 'Whoops!')
+    click_button('Cancel')
 
-    page.accept_alert 'Are you sure you want to cancel creating this comment?' do
-      click_button('Cancel')
+    page.within('.modal') do
+      click_button('OK', match: :first)
     end
 
     wait_for_requests