fix: remove preview sites from allowed embedding pages (overhangio#25)

This is because the preview pages have been migrated to the learning MFE and now do not run on a separate domain

Author: Danyal-Faheem

changelog.d/20250521_190353_danyal.faheem_remove_preview.md

@@ -0,0 +1 @@
+- 💥[Improvement] Remove preview sites from allowed embedding pages as the preview page has been migrated to the learning MFE. (by @Danyal-Faheem)

tutorjupyter/templates/jupyter/apps/jupyterhub_config.py

@@ -29,8 +29,6 @@
     "{% if ENABLE_HTTPS %}https{% else %}http{% endif %}://{{ LMS_HOST }}:8000",
     "{% if ENABLE_HTTPS %}https{% else %}http{% endif %}://{{ CMS_HOST }}",
     "{% if ENABLE_HTTPS %}https{% else %}http{% endif %}://{{ CMS_HOST }}:8001",
-    "{% if ENABLE_HTTPS %}https{% else %}http{% endif %}://{{ PREVIEW_LMS_HOST }}",
-    "{% if ENABLE_HTTPS %}https{% else %}http{% endif %}://{{ PREVIEW_LMS_HOST }}:8000",
 ]
 {% if MFE_HOST is defined %}
 frame_ancestors += [