Make file uploads after a preview work. (#4557)

Fixes #4556

We need to test that removing `form.delete_temporary_files()` from
`render_preview` does not have any bad side effects. My guess is that it
is conflicting with (not needed after)
#4499.

Author: frjo

hypha/apply/funds/views/submission_edit.py

@@ -97,10 +97,6 @@ def render_preview(self, request: HttpRequest, form: BaseModelForm) -> HttpRespo
         self.object.create_revision(draft=True, by=request.user)
         messages.success(self.request, _("Draft saved"))
 
-        # Required for django-file-form: delete temporary files for the new files
-        # uploaded while edit.
-        form.delete_temporary_files()
-
         context = self.get_context_data()
         return render(request, "funds/application_preview.html", context)