Revert "Fix rendering of parent row when update form for a different controller is submitted. (Note: Perhaps the :parent_controller parameter is intended for embedded scaffolds only, and I've been misusing it.)"

The hack was tweaked in commit c09e9154d7763b8af8e60b6112ec9230758ee0dd of options_db. Because it is dubious and somewhat application-specific, it has been moved to options_db; see config/initializers/active_scaffold_controller_helpers_patch.rb

This reverts commit c09e9154d7763b8af8e60b6112ec9230758ee0dd.