Revert temporal primary keys and foreign keys

This feature set did not handle empty ranges correctly, and it's now
too late for PostgreSQL 17 to fix it.

The following commits are reverted:

    6db4598fcb Add stratnum GiST support function
    46a0cd4cef Add temporal PRIMARY KEY and UNIQUE constraints
    86232a49a4 Fix comment on gist_stratnum_btree
    030e10ff1a Rename pg_constraint.conwithoutoverlaps to conperiod
    a88c800deb Use daterange and YMD in without_overlaps tests instead of tsrange.
    5577a71fb0 Use half-open interval notation in without_overlaps tests
    34768ee361 Add temporal FOREIGN KEY contraints
    482e108cd3 Add test for REPLICA IDENTITY with a temporal key
    c3db1f30cb doc:  clarify PERIOD and WITHOUT OVERLAPS in CREATE TABLE
    144c2ce0cc Fix ON CONFLICT DO NOTHING/UPDATE for temporal indexes

Discussion: https://www.postgresql.org/message-id/d0b64a7a-dfe4-4b84-a906-c7dedfa40a3e@eisentraut.org

src/include/access/gist.h

@@ -17,7 +17,6 @@
 #define GIST_H
 
 #include "access/itup.h"
-#include "access/stratnum.h"
 #include "access/transam.h"
 #include "access/xlog.h"
 #include "access/xlogdefs.h"
@@ -39,8 +38,7 @@
 #define GIST_FETCH_PROC					9
 #define GIST_OPTIONS_PROC				10
 #define GIST_SORTSUPPORT_PROC			11
-#define GIST_STRATNUM_PROC				12
-#define GISTNProcs					12
+#define GISTNProcs					11
 
 /*
  * Page opaque data in a GiST index page.
@@ -247,6 +245,4 @@ typedef struct
 	do { (e).key = (k); (e).rel = (r); (e).page = (pg); \
 		 (e).offset = (o); (e).leafkey = (l); } while (0)
 
-extern StrategyNumber GistTranslateStratnum(Oid opclass, StrategyNumber strat);
-
 #endif							/* GIST_H */