Fix the test 003_logical_slots.

pg_upgrade test 003_logical_slots was leaving files like
delete_old_cluster.sh in the source directory for VPATH and meson builds.
The fix is to change the directory to tmp_check before running the test as
is done in the similar test in 002_pg_upgrade.

Reported-by: Peter Eisentraut, Andrew Dunstan
Author: Hayato Kuroda based on a suggestion by Andrew Dunstan
Reviewed-by: Peter Smith, Hou Zhijie
Discussion: http://postgr.es/m/b4fb612d-ef0b-4db7-81b9-cf0701275491@eisentraut.org
Discussion: http://postgr.es/m/TYAPR01MB5866D7B89DC5688256D980C2F5A9A@TYAPR01MB5866.jpnprd01.prod.outlook.com

src/bin/pg_upgrade/t/003_logical_slots.pl

@@ -34,6 +34,11 @@ my @pg_upgrade_cmd = (
 	'-P', $newpub->port,
 	$mode);
 
+# In a VPATH build, we'll be started in the source directory, but we want
+# to run pg_upgrade in the build directory so that any files generated finish
+# in it, like delete_old_cluster.{sh,bat}.
+chdir ${PostgreSQL::Test::Utils::tmp_check};
+
 # ------------------------------
 # TEST: Confirm pg_upgrade fails when the new cluster has wrong GUC values