Revert "[feat]: Surface deletionTimestamp as a printcolumn"

[jonasz-lasut]

Reverts #514

Objections raised:

• Being-deleted is a rare state in a resource's lifecycle; the info is already obtainable via kubectl with extra flags; most Kubernetes resources don't surface this at all; there's no defined policy for what qualifies as a print column, which risks scope creep ("what about other fields people ask for?"). Not strongly opposed, but flags the implications.
• The approach only works for upjet-based providers' MRs, not CRs generally, and printing a deletion
  column isn't a common CR convention.
• The Ready condition already sets reason: Deleting when a resource is being deleted. They currently print the
  Ready status (True/False) but not the reason, the Ready condition/reason is a better lifecycle signal than a dedicated column.

Long term proposal is to introduce crd_types template similarly as with controller and setup templates