Update ee/app/views/shared/billings/_billing_plan.html.haml,...

Update ee/app/views/shared/billings/_billing_plan.html.haml, ee/app/views/shared/billings/_billing_plan_header.html.haml files

ee/app/views/shared/billings/_billing_plan.html.haml

@@ -35,7 +35,7 @@
       .card-footer.p-3
         .float-right{ class: ("invisible" unless purchase_link.action == 'upgrade' || is_current_plan) }
           - if show_contact_sales_button?(purchase_link.action)
-            = link_to s_('BillingPlan|Contact sales'), "#{contact_sales_url}?test=inappcontactsales#{plan.code}", class: "btn btn-success btn-inverted", data: { **experiment_tracking_data_for_button_click('contact_sales') }
+            = link_to s_('BillingPlan|Contact sales'), "#{contact_sales_url}?test=inappcontactsales#{plan.code}", class: "btn btn-success-secondary gl-button", data: { **experiment_tracking_data_for_button_click('contact_sales') }
           - upgrade_button_class = "disabled" if is_current_plan && !namespace.trial_active?
           - cta_class = '-new' if use_new_purchase_flow?(namespace)
-          = link_to s_('BillingPlan|Upgrade'), plan_purchase_or_upgrade_url(namespace, plan, current_plan), class: "btn btn-success #{upgrade_button_class} billing-cta-purchase#{cta_class}", data: { **experiment_tracking_data_for_button_click('upgrade') }
+          = link_to s_('BillingPlan|Upgrade'), plan_purchase_or_upgrade_url(namespace, plan, current_plan), class: "btn btn-success gl-button #{upgrade_button_class} billing-cta-purchase#{cta_class}", data: { **experiment_tracking_data_for_button_click('upgrade') }

ee/app/views/shared/billings/_billing_plan_header.html.haml

@@ -24,10 +24,10 @@
     %p= s_("BillingPlans|This group uses the plan associated with its parent group.")
     - parent_billing_page_link = link_to parent_group.full_name, group_billings_path(parent_group)
     %p= s_("BillingPlans|To manage the plan for this group, visit the billing section of %{parent_billing_page_link}.").html_safe % { parent_billing_page_link: parent_billing_page_link }
-    = link_to s_("BillingPlans|Manage plan"), group_billings_path(parent_group), class: 'btn btn-success'
+    = link_to s_("BillingPlans|Manage plan"), group_billings_path(parent_group), class: 'btn btn-success gl-button'
   - else
     = render 'shared/billings/trial_status', namespace: namespace
 
   - if namespace.eligible_for_trial?
     - glm_content = namespace_for_user ? 'user-billing' : 'group-billing'
-    %p= link_to 'Start your free trial', new_trial_registration_path(glm_source: 'gitlab.com', glm_content: glm_content), class: 'btn btn-primary'
+    %p= link_to 'Start your free trial', new_trial_registration_path(glm_source: 'gitlab.com', glm_content: glm_content), class: 'btn btn-primary gl-button'