fix: Remove edX-specific reference

Remove edx-Specific reference from email confirmation banner.

Author: arbrandes

src/containers/LearnerDashboardHeader/ConfirmEmailBanner/__snapshots__/index.test.jsx.snap

@@ -10,7 +10,7 @@ exports[`ConfirmEmailBanner snapshot Show on unverified 1`] = `
     <format-message-function
       message={
         Object {
-          "defaultMessage": "Remember to confirm your email so that you can keep learning on edX! {confirmNowButton}.",
+          "defaultMessage": "Remember to confirm your email so that you can keep learning! {confirmNowButton}.",
           "description": "Text for reminding user to confirm email",
           "id": "leanerDashboard.confirmEmailTextReminderBanner",
         }

src/containers/LearnerDashboardHeader/ConfirmEmailBanner/messages.js

@@ -9,7 +9,7 @@ const messages = defineMessages({
   confirmEmailTextReminderBanner: {
     id: 'leanerDashboard.confirmEmailTextReminderBanner',
     description: 'Text for reminding user to confirm email',
-    defaultMessage: 'Remember to confirm your email so that you can keep learning on edX! {confirmNowButton}.',
+    defaultMessage: 'Remember to confirm your email so that you can keep learning! {confirmNowButton}.',
   },
   verifiedConfirmEmailButton: {
     id: 'leanerDashboard.verifiedConfirmEmailButton',