Remove unnecessary checkpoint from PL regression tests. This was once

handy to prevent core dump files from disappearing, but it's useless now
because (a) we don't drop core in individual DB subdirectories anymore,
and (b) CREATE DATABASE forces an internal checkpoint anyway.

src/pl/plperl/expected/plperl.out

 --
--- checkpoint so that if we have a crash in the tests, replay of the
--- just-completed CREATE DATABASE won't discard the core dump file
---
-checkpoint;
---
 -- Test result value processing
 --
 CREATE OR REPLACE FUNCTION perl_int(int) RETURNS INTEGER AS $$
@@ -428,7 +423,7 @@ CREATE OR REPLACE FUNCTION  array_of_text() RETURNS TEXT[][]
 LANGUAGE plperl as $$ 
     return [['a"b',undef,'c,d'],['e\\f',undef,'g']]; 
 $$;
-SELECT array_of_text(); 
+SELECT array_of_text();
              array_of_text             
 ---------------------------------------
  {{"a\"b",NULL,"c,d"},{"e\\f",NULL,g}}

src/pl/plperl/sql/plperl.sql

---
--- checkpoint so that if we have a crash in the tests, replay of the
--- just-completed CREATE DATABASE won't discard the core dump file
---
-checkpoint;
-
 --
 -- Test result value processing
 --

src/pl/tcl/expected/pltcl_setup.out

 --
--- checkpoint so that if we have a crash in the tests, replay of the
--- just-completed CREATE DATABASE won't discard the core dump file
---
-checkpoint;
---
 -- Create the tables used in the test queries
 --
 -- T_pkey1 is the primary key table for T_dta1. Entries from T_pkey1

src/pl/tcl/sql/pltcl_setup.sql

---
--- checkpoint so that if we have a crash in the tests, replay of the
--- just-completed CREATE DATABASE won't discard the core dump file
---
-checkpoint;
-
 --
 -- Create the tables used in the test queries
 --