Update deprecated project header buttons

ee/app/assets/javascripts/environments_dashboard/components/dashboard/project_header.vue

 <script>
-import { GlTooltipDirective, GlLink, GlDeprecatedButton } from '@gitlab/ui';
+import { GlTooltipDirective, GlLink, GlButton } from '@gitlab/ui';
 import { s__ } from '~/locale';
 import Icon from '~/vue_shared/components/icon.vue';
 import ProjectAvatar from '~/vue_shared/components/project_avatar/default.vue';
@@ -9,7 +9,7 @@ export default {
     Icon,
     ProjectAvatar,
     GlLink,
-    GlDeprecatedButton,
+    GlButton,
   },
   directives: {
     GlTooltip: GlTooltipDirective,
@@ -58,9 +58,9 @@ export default {
       </button>
       <ul class="dropdown-menu dropdown-menu-right">
         <li>
-          <gl-deprecated-button class="js-remove-button" @click="onRemove()">
+          <gl-button class="js-remove-button" variant="link" @click="onRemove()">
             <span class="text-danger"> {{ $options.removeProjectText }} </span>
-          </gl-deprecated-button>
+          </gl-button>
         </li>
       </ul>
     </div>

ee/spec/frontend/environments_dashboard/components/__snapshots__/project_header_spec.js.snap

@@ -67,17 +67,19 @@ exports[`Project Header matches the snapshot 1`] = `
       class="dropdown-menu dropdown-menu-right"
     >
       <li>
-        <gl-deprecated-button-stub
+        <gl-button-stub
+          category="tertiary"
           class="js-remove-button"
-          size="md"
-          variant="secondary"
+          icon=""
+          size="medium"
+          variant="link"
         >
           <span
             class="text-danger"
           >
              Remove 
           </span>
-        </gl-deprecated-button-stub>
+        </gl-button-stub>
       </li>
     </ul>
   </div>

ee/spec/frontend/environments_dashboard/components/project_header_spec.js

 import { shallowMount } from '@vue/test-utils';
-import { GlDeprecatedButton } from '@gitlab/ui';
+import { GlButton } from '@gitlab/ui';
 import component from 'ee/environments_dashboard/components/dashboard/project_header.vue';
 import ProjectAvatar from '~/vue_shared/components/project_avatar/default.vue';
 
@@ -79,7 +79,7 @@ describe('Project Header', () => {
         .filter(w => w.text() === 'Remove');
       removeLink
         .at(0)
-        .find(GlDeprecatedButton)
+        .find(GlButton)
         .vm.$emit('click');
 
       return wrapper.vm.$nextTick().then(() => {