fix: AA-663: Update header text for CourseCompletion (#421)

If the marketing url is not set, we shouldn't have a message
about sharing.

src/courseware/course/course-exit/CourseCelebration.jsx

@@ -45,6 +45,7 @@ function CourseCelebration({ intl }) {
     certificateData,
     end,
     linkedinAddToProfileUrl,
+    marketingUrl,
     offer,
     org,
     relatedPrograms,
@@ -287,7 +288,8 @@ function CourseCelebration({ intl }) {
           {intl.formatMessage(messages.congratulationsHeader)}
         </div>
         <div className="col-12 p-0 font-weight-normal lead text-center">
-          {intl.formatMessage(messages.shareHeader)}
+          {intl.formatMessage(messages.completedCourseHeader)}
+          {marketingUrl && ` ${intl.formatMessage(messages.shareMessage)}`}
           <SocialIcons
             analyticsId="edx.ui.lms.course_exit.social_share.clicked"
             className="mt-2"

src/courseware/course/course-exit/messages.js

@@ -35,6 +35,10 @@ const messages = defineMessages({
     defaultMessage: 'Sample certificate',
     description: 'Alt text used to describe an image of a certificate',
   },
+  completedCourseHeader: {
+    id: 'courseCelebration.completedCourseHeader',
+    defaultMessage: 'You have completed your course.',
+  },
   congratulationsHeader: {
     id: 'courseCelebration.congratulationsHeader',
     defaultMessage: 'Congratulations!',
@@ -127,9 +131,9 @@ const messages = defineMessages({
     defaultMessage: 'Search our catalog',
     description: 'First part of a sentence that continues afterward',
   },
-  shareHeader: {
-    id: 'courseCelebration.shareHeader',
-    defaultMessage: 'You have completed your course. Share your success on social media or email.',
+  shareMessage: {
+    id: 'courseCelebration.shareMessage',
+    defaultMessage: 'Share your success on social media or email.',
   },
   socialMessage: {
     id: 'courseExit.social.shareCompletionMessage',