Merge branch 'upgrade-bootstrap-vue/specs-update-design-management' into 'master'

Make EE design management specs compatible w/ BootstrapVue 2

See merge request gitlab-org/gitlab!19907

ee/spec/frontend/design_management/components/upload/button_spec.js

@@ -6,6 +6,7 @@ describe('Design management upload button component', () => {
 
   function createComponent(isSaving = false, isInverted = false) {
     wrapper = shallowMount(UploadButton, {
+      attachToDocument: true,
       sync: false,
       propsData: {
         isSaving,