Reduce running time of jsonb_sqljson test

The test created a 1m row table in order to test parallel operation of
JSON_VALUE. However, this was more than were needed for the test, so
save time by halving it, and also by making the table unlogged.
Experimentation shows that this size is only a little above the number
required to generate the expected output.

Per gripe from Andres Freund

Discussion: https://postgr.es/m/20220406022118.3ocqvhxr6kciw5am@alap3.anarazel.de

src/test/regress/expected/jsonb_sqljson.out

@@ -2088,9 +2088,9 @@ ERROR:  only string constants supported in JSON_TABLE path specification
 LINE 1: SELECT * FROM JSON_TABLE(jsonb '{"a": 123}', '$' || '.' || '...
                                                      ^
 -- Test parallel JSON_VALUE()
-CREATE TABLE test_parallel_jsonb_value AS
+CREATE UNLOGGED TABLE test_parallel_jsonb_value AS
 SELECT i::text::jsonb AS js
-FROM generate_series(1, 1000000) i;
+FROM generate_series(1, 500000) i;
 -- Should be non-parallel due to subtransactions
 EXPLAIN (COSTS OFF)
 SELECT sum(JSON_VALUE(js, '$' RETURNING numeric)) FROM test_parallel_jsonb_value;
@@ -2103,7 +2103,7 @@ SELECT sum(JSON_VALUE(js, '$' RETURNING numeric)) FROM test_parallel_jsonb_value
 SELECT sum(JSON_VALUE(js, '$' RETURNING numeric)) FROM test_parallel_jsonb_value;
      sum      
 --------------
- 500000500000
+ 125000250000
 (1 row)
 
 -- Should be parallel
@@ -2121,6 +2121,6 @@ SELECT sum(JSON_VALUE(js, '$' RETURNING numeric ERROR ON ERROR)) FROM test_paral
 SELECT sum(JSON_VALUE(js, '$' RETURNING numeric ERROR ON ERROR)) FROM test_parallel_jsonb_value;
      sum      
 --------------
- 500000500000
+ 125000250000
 (1 row)
 

src/test/regress/sql/jsonb_sqljson.sql

@@ -948,9 +948,9 @@ SELECT JSON_QUERY(jsonb '{"a": 123}', 'error' || ' ' || 'error');
 SELECT * FROM JSON_TABLE(jsonb '{"a": 123}', '$' || '.' || 'a' COLUMNS (foo int));
 
 -- Test parallel JSON_VALUE()
-CREATE TABLE test_parallel_jsonb_value AS
+CREATE UNLOGGED TABLE test_parallel_jsonb_value AS
 SELECT i::text::jsonb AS js
-FROM generate_series(1, 1000000) i;
+FROM generate_series(1, 500000) i;
 
 -- Should be non-parallel due to subtransactions
 EXPLAIN (COSTS OFF)