style: banner height reduced to space screen size (#30241)

lms/templates/discussion/_switch_experience_fragment.html

@@ -7,13 +7,13 @@ from django.utils.translation import ugettext as _
 %>
 
 % if show_banner:
-<div class="upgrade-banner d-flex bg-primary text-white align-items-center px-4 py-3">
+<div class="upgrade-banner d-flex bg-primary text-white align-items-center px-4">
     % if show_mfe:
-    <div class="d-flex w-100">
+    <div class="d-flex w-100 small">
         ${_("You are viewing an educator only preview of the new discussions experience!")}
     </div>
     % else:
-    <div class="d-flex w-100">
+    <div class="d-flex w-100 small">
         ${_("An educator preview of new discussions experience is available!")}
     </div>
     %endif