Rework how the remappings middleware matches remapped to/from columns for explicit external (FK) remaps (#20009)

* Fix #9236 [WIP]

* Revert unneeded changes

* Only merge namespaced :options into result info

* Revert unneeded changes

* Everything is working 

* Revert unneeded change

* Clean namespaces

* Add `:test` profile to `namespace-checker` to suppress log messages.

* PR feedback

* Fix namespaces