Use gl-button on cluster advanced settings page

Resolves https://gitlab.com/gitlab-org/gitlab/-/issues/259251

app/views/clusters/clusters/_advanced_settings.html.haml

@@ -24,7 +24,7 @@
         .text-muted
           = html_escape(s_('ClusterIntegration|A cluster management project can be used to run deployment jobs with Kubernetes %{code_open}cluster-admin%{code_close} privileges.')) % { code_open: '<code>'.html_safe, code_close: '</code>'.html_safe }
           = link_to _('More information'), help_page_path('user/clusters/management_project.md'), target: '_blank'
-      = field.submit _('Save changes'), class: 'btn btn-success'
+      = field.submit _('Save changes'), class: 'btn gl-button btn-success'
 
   .sub-section.form-group
     %h4
@@ -35,7 +35,7 @@
         = s_("ClusterIntegration|This is necessary if your integration has become out of sync. The cache is repopulated during the next CI job that requires namespace and service accounts.")
       - else
         = s_("ClusterIntegration|This is necessary to clear existing environment-namespace associations from clusters previously managed by GitLab.")
-    = link_to(s_('ClusterIntegration|Clear cluster cache'), clusterable.clear_cluster_cache_path(@cluster), method: :delete, class: 'btn btn-primary')
+    = link_to(s_('ClusterIntegration|Clear cluster cache'), clusterable.clear_cluster_cache_path(@cluster), method: :delete, class: 'btn gl-button btn-info')
 
   .sub-section.form-group
     %h4.text-danger