Merge pull request #10781 from edx/awais786/ECOM-2980-admin-certs-page

Replacing user dropdown field with user search textbox. On stage due …

lms/djangoapps/certificates/admin.py

@@ -52,6 +52,7 @@ class GeneratedCertificateAdmin(admin.ModelAdmin):
     """
     Django admin customizations for GeneratedCertificate model
     """
+    raw_id_fields = ('user',)
     search_fields = ('course_id', 'user__username')
     list_display = ('id', 'course_id', 'mode', 'user')