Fix the test 003_logical_slots.

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