[REV-1205] Add upsell tracking to verified/no SKU courses on the dashboard

Add the tracking class to the upsell button on the course dashboard for courses that are verified but have no SKUs so we get better data on when upsell links get clicked.

lms/templates/dashboard/_dashboard_course_listing.html

@@ -416,7 +416,7 @@ from lms.djangoapps.experiments.utils import UPSELL_TRACKING_FLAG
                 % if use_ecommerce_payment_flow and course_mode_info['verified_sku']:
                   <a class="action action-upgrade track_course_dashboard_green_button" href="${ecommerce_payment_page}?sku=${course_mode_info['verified_sku']}">
                 % else:
-                  <a class="action action-upgrade" href="${reverse('verify_student_upgrade_and_verify', kwargs={'course_id': six.text_type(course_overview.id)})}" data-course-id="${course_overview.id}" data-user="${user.username}">
+                  <a class="action action-upgrade track_course_dashboard_green_button" href="${reverse('verify_student_upgrade_and_verify', kwargs={'course_id': six.text_type(course_overview.id)})}" data-course-id="${course_overview.id}" data-user="${user.username}">
                 % endif
                     <span class="action-upgrade-icon" aria-hidden="true"></span>
                   <span class="wrapper-copy">