Add gl-button to services/prometheus

app/views/projects/services/prometheus/_configuration_banner.html.haml

@@ -14,13 +14,13 @@
         .col-sm-10
           %p.text-success.gl-mt-3
             = s_('PrometheusService|Prometheus is being automatically managed on your clusters')
-          = link_to s_('PrometheusService|Manage clusters'), project_clusters_path(project), class: 'btn'
+          = link_to s_('PrometheusService|Manage clusters'), project_clusters_path(project), class: 'btn gl-button'
       - else
         .col-sm-2
           = image_tag 'illustrations/monitoring/loading.svg'
         .col-sm-10
           %p.gl-mt-3
             = s_('PrometheusService|Automatically deploy and configure Prometheus on your clusters to monitor your project’s environments')
-          = link_to s_('PrometheusService|Install Prometheus on clusters'), project_clusters_path(project), class: 'btn btn-success'
+          = link_to s_('PrometheusService|Install Prometheus on clusters'), project_clusters_path(project), class: 'btn gl-button btn-success'
 
 %hr

app/views/projects/services/prometheus/_custom_metrics.html.haml

@@ -13,7 +13,7 @@
       -# haml-lint:disable NoPlainNodes
       %span.badge.badge-pill.js-custom-monitored-count 0
       -# haml-lint:enable NoPlainNodes
-      = link_to s_('PrometheusService|New metric'), new_project_prometheus_metric_path(project), class: 'btn btn-success js-new-metric-button hidden', data: { qa_selector: 'new_metric_button' }
+      = link_to s_('PrometheusService|New metric'), new_project_prometheus_metric_path(project), class: 'btn gl-button btn-success js-new-metric-button hidden', data: { qa_selector: 'new_metric_button' }
     .card-body
       .flash-container.hidden
         .flash-warning