Migrate to GlButton in approvals footer

ee/app/assets/javascripts/vue_merge_request_widget/components/approvals/approvals_footer.vue

 <script>
-import { GlButton, GlDeprecatedButton } from '@gitlab/ui';
+import { GlButton } from '@gitlab/ui';
 import { __ } from '~/locale';
 import UserAvatarList from '~/vue_shared/components/user_avatar/user_avatar_list.vue';
 import ApprovalsList from './approvals_list.vue';
@@ -7,7 +7,6 @@ import ApprovalsList from './approvals_list.vue';
 export default {
   components: {
     GlButton,
-    GlDeprecatedButton,
     UserAvatarList,
     ApprovalsList,
   },
@@ -81,14 +80,14 @@ export default {
       />
       <template v-if="isCollapsed">
         <user-avatar-list :items="suggestedApproversTrimmed" :breakpoint="0" empty-text="" />
-        <gl-deprecated-button variant="link" @click="toggle">{{
+        <gl-button data-testid="approvers-expand-button" variant="link" @click="toggle">{{
           __('View eligible approvers')
-        }}</gl-deprecated-button>
+        }}</gl-button>
       </template>
       <template v-else>
-        <gl-deprecated-button variant="link" @click="toggle">{{
+        <gl-button data-testid="approvers-collapse-button" variant="link" @click="toggle">{{
           __('Collapse')
-        }}</gl-deprecated-button>
+        }}</gl-button>
       </template>
     </div>
     <div v-if="!isCollapsed && approvalRules.length" class="border-top">

ee/spec/frontend/vue_mr_widget/components/approvals/approvals_footer_spec.js

-import { GlDeprecatedButton, GlButton, GlLoadingIcon, GlIcon } from '@gitlab/ui';
+import { GlButton, GlLoadingIcon, GlIcon } from '@gitlab/ui';
 import { mount } from '@vue/test-utils';
 import ApprovalsFooter from 'ee/vue_merge_request_widget/components/approvals/approvals_footer.vue';
 import ApprovalsList from 'ee/vue_merge_request_widget/components/approvals/approvals_list.vue';
@@ -28,8 +28,8 @@ describe('EE MRWidget approvals footer', () => {
   const findToggle = () => wrapper.find(GlButton);
   const findToggleIcon = () => findToggle().find(GlIcon);
   const findToggleLoadingIcon = () => findToggle().find(GlLoadingIcon);
-  const findExpandButton = () => wrapper.find(GlDeprecatedButton);
-  const findCollapseButton = () => wrapper.find(GlDeprecatedButton);
+  const findExpandButton = () => wrapper.find('[data-testid="approvers-expand-button"]');
+  const findCollapseButton = () => wrapper.find('[data-testid="approvers-collapse-button"]');
   const findList = () => wrapper.find(ApprovalsList);
   const findAvatars = () => wrapper.find(UserAvatarList);