🐛(frontend) fix Enroll now translation

[igobranco]

When using an external LMS, the CTA Enroll now on course runs isn't being translated.

Replace #2246

Screenshot on French, is still showing the Enroll now on English.

Fixed version:

The course run needs to have something completely different URL that don't match the course regex configured.
Ex: https://lms.nau.edu.pt/course_modes/choose/course-v1:NOVA+FEEF+2023_T2/

To test locally, it requires to add to the file src/frontend/i18n/locales/fr-FR.json

  "components.SyllabusCourseRun.enrollNow": {
    "description": "CTA for users to enroll on ongoing of future open course.",
    "message": "S'inscrire maintenant"
  },
  "components.SyllabusCourseRunCompacted.enrollNow": {
    "description": "CTA for users to enroll on ongoing of future open course.",
    "message": "S'inscrire maintenant"
  }