Use pg_stat_get_xact* functions within xacts

Resolve build farm failures from c203d6cf,
diagnosed by Tom Lane.

The output of pg_stat_get_xact_tuples_hot_updated() and friends
is not guaranteed to show anything after the transaction completes.
Data is flushed slowly to stats collector, so using them can
give timing issues.

src/test/regress/expected/func_index.out

+begin;
 create table keyvalue(id integer primary key, info jsonb);
 create index nameindex on keyvalue((info->>'name')) with (recheck_on_update=false);
 insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
@@ -8,7 +9,8 @@ select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
                                    0
 (1 row)
 
-drop table keyvalue;
+rollback;
+begin;
 create table keyvalue(id integer primary key, info jsonb);
 create index nameindex on keyvalue((info->>'name')) with (recheck_on_update=true);
 insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
@@ -33,7 +35,8 @@ select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
                                    2
 (1 row)
 
-drop table keyvalue;
+rollback;
+begin;
 create table keyvalue(id integer primary key, info jsonb);
 create index nameindex on keyvalue((info->>'name'));
 insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
@@ -58,4 +61,4 @@ select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
                                    2
 (1 row)
 
-drop table keyvalue;
+rollback;

src/test/regress/sql/func_index.sql

+begin;
 create table keyvalue(id integer primary key, info jsonb);
 create index nameindex on keyvalue((info->>'name')) with (recheck_on_update=false);
 insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
 update keyvalue set info='{"name": "john", "data": "some other data"}' where id=1;
 select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
-drop table keyvalue;
+rollback;
 
+begin;
 create table keyvalue(id integer primary key, info jsonb);
 create index nameindex on keyvalue((info->>'name')) with (recheck_on_update=true);
 insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
@@ -14,8 +16,9 @@ update keyvalue set info='{"name": "smith", "data": "some other data"}' where id
 select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
 update keyvalue set info='{"name": "smith", "data": "some more data"}' where id=1;
 select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
-drop table keyvalue;
+rollback;
 
+begin;
 create table keyvalue(id integer primary key, info jsonb);
 create index nameindex on keyvalue((info->>'name'));
 insert into keyvalue values (1, '{"name": "john", "data": "some data"}');
@@ -25,6 +28,6 @@ update keyvalue set info='{"name": "smith", "data": "some other data"}' where id
 select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
 update keyvalue set info='{"name": "smith", "data": "some more data"}' where id=1;
 select pg_stat_get_xact_tuples_hot_updated('keyvalue'::regclass);
-drop table keyvalue;
+rollback;