use class selector instead of id selector for course_dashboard_green button (#24471)

Replaced the id selector used for tracking the course_dashboard_green button with a class selector instead, so we get eventing on each button per course on the course dashboard page.

lms/templates/dashboard/_dashboard_course_listing.html

@@ -414,7 +414,7 @@ from lms.djangoapps.experiments.utils import UPSELL_TRACKING_FLAG
               </p>
               <div class="action-upgrade-container">
                 % if use_ecommerce_payment_flow and course_mode_info['verified_sku']:
-                  <a id="ecommerce_upgrade_link" class="action action-upgrade" href="${ecommerce_payment_page}?sku=${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}">
                 % endif
@@ -463,7 +463,7 @@ from lms.djangoapps.experiments.utils import UPSELL_TRACKING_FLAG
       if (window.loadedECommerceEvents === undefined) {
         window.loadedECommerceEvents = true;
 
-        TrackECommerceEvents.trackUpsellClick($("#ecommerce_upgrade_link"), 'course_dashboard_green', {
+        TrackECommerceEvents.trackUpsellClick($(".track_course_dashboard_green_button"), 'course_dashboard_green', {
           pageName: "course_dashboard",
           linkType: "button",
           linkCategory: "green_upgrade"