Delete unused .btn-action classes

Delete usages of this class which were probably meant to be
deleted when the UI changed

app/assets/javascripts/label_manager.js

@@ -2,8 +2,7 @@
 
 import $ from 'jquery';
 import Sortable from 'sortablejs';
-
-import { hide, dispose } from '~/tooltips';
+import { dispose } from '~/tooltips';
 import { deprecatedCreateFlash as flash } from './flash';
 import axios from './lib/utils/axios_utils';
 import { __ } from './locale';
@@ -30,7 +29,6 @@ export default class LabelManager {
   }
 
   bindEvents() {
-    this.prioritizedLabels.find('.btn-action').on('mousedown', this, this.onButtonActionClick);
     return this.togglePriorityButton.on('click', this, this.onTogglePriorityClick);
   }
 
@@ -46,11 +44,6 @@ export default class LabelManager {
     _this.toggleEmptyState($label, $btn, action);
   }
 
-  onButtonActionClick(e) {
-    e.stopPropagation();
-    hide(e.currentTarget);
-  }
-
   toggleEmptyState() {
     this.emptyState.classList.toggle(
       'hidden',

app/views/shared/_label.html.haml

@@ -29,7 +29,7 @@
             %ul
               - if label.project_label? && label.project.group && can?(current_user, :admin_label, label.project.group)
                 %li
-                  %button.js-promote-project-label-button.btn.btn-transparent.btn-action{ disabled: true, type: 'button',
+                  %button.js-promote-project-label-button.btn.btn-transparent{ disabled: true, type: 'button',
                     data: { url: promote_project_label_path(label.project, label),
                             label_title: label.title,
                             label_color: label.color,

app/views/shared/milestones/_labels_tab.html.haml

@@ -8,7 +8,7 @@
         = markdown_field(label, :description)
 
       .float-right.d-none.d-lg-block
-        = link_to milestones_issues_path(options.merge(state: 'opened')), class: 'btn gl-button btn-default-tertiary btn-action' do
+        = link_to milestones_issues_path(options.merge(state: 'opened')), class: 'btn gl-button btn-default-tertiary' do
           - pluralize milestone_issues_by_label_count(@milestone, label, state: :opened), _('open issue')
-        = link_to milestones_issues_path(options.merge(state: 'closed')), class: 'btn gl-button btn-default-tertiary btn-action' do
+        = link_to milestones_issues_path(options.merge(state: 'closed')), class: 'btn gl-button btn-default-tertiary' do
           - pluralize milestone_issues_by_label_count(@milestone, label, state: :closed), _('closed issue')