Remove gratuitous environment dependency in 002_types.pl test.

Computing related timestamps by subtracting "N days" is sensitive
to the prevailing timezone, since we interpret that as "same local
time on the N'th prior day".  Even though the intervals in question
are only two to four days, through remarkable bad luck they managed
to cross the end of Ramadan in 2014, causing the test's output to
change if timezone is set to Africa/Casablanca.  (Maybe in other
Muslim areas as well; I didn't check.)  There's absolutely no reason
for this test to exercise interval subtraction, so just get rid of
that and use plain timestamptz constants representing the intended
values.

Per report from Andres Freund.  Back-patch to v10 where this test
script came in.

Discussion: https://postgr.es/m/20210930183641.7lh4jhvpipvromca@alap3.anarazel.de

src/test/subscription/t/002_types.pl

@@ -237,9 +237,9 @@ $node_publisher->safe_psql(
 	-- test_tbl_range_array
 	INSERT INTO tst_range_array (a, b, c) VALUES
 		(1, tstzrange('Mon Aug 04 00:00:00 2014 CEST'::timestamptz, 'infinity'), '{"[1,2]", "[10,20]"}'),
-		(2, tstzrange('Mon Aug 04 00:00:00 2014 CEST'::timestamptz - interval '2 days', 'Mon Aug 04 00:00:00 2014 CEST'::timestamptz), '{"[2,3]", "[20,30]"}'),
-		(3, tstzrange('Mon Aug 04 00:00:00 2014 CEST'::timestamptz - interval '3 days', 'Mon Aug 04 00:00:00 2014 CEST'::timestamptz), '{"[3,4]"}'),
-		(4, tstzrange('Mon Aug 04 00:00:00 2014 CEST'::timestamptz - interval '4 days', 'Mon Aug 04 00:00:00 2014 CEST'::timestamptz), '{"[4,5]", NULL, "[40,50]"}'),
+		(2, tstzrange('Sat Aug 02 00:00:00 2014 CEST'::timestamptz, 'Mon Aug 04 00:00:00 2014 CEST'::timestamptz), '{"[2,3]", "[20,30]"}'),
+		(3, tstzrange('Fri Aug 01 00:00:00 2014 CEST'::timestamptz, 'Mon Aug 04 00:00:00 2014 CEST'::timestamptz), '{"[3,4]"}'),
+		(4, tstzrange('Thu Jul 31 00:00:00 2014 CEST'::timestamptz, 'Mon Aug 04 00:00:00 2014 CEST'::timestamptz), '{"[4,5]", NULL, "[40,50]"}'),
 		(5, NULL, NULL);
 
 	-- tst_hstore