Revert "Add key management system" (
978f869b99) & later commits
The patch needs test cases, reorganization, and cfbot testing.
Technically reverts commits
5c31afc49d..
e35b2bad1a (exclusive/inclusive)
and
08db7c63f3..
ccbe34139b.
Reported-by: Tom Lane, Michael Paquier
Discussion: https://postgr.es/m/E1ktAAG-0002V2-VB@gemulon.postgresql.org