Make pltcl regression tests safe for Danish locale.

Another peculiarity of Danish locale is that it has an unusual idea
of how to sort upper vs. lower case.  One of the pltcl test cases has
an issue with that.  Now that COLLATE works in all supported branches,
we can just change the test to be locale-independent, and get rid of
the variant expected file that used to support non-C locales.

src/pl/tcl/expected/pltcl_queries.out

@@ -163,7 +163,7 @@ select 100 @< 4;
  f
 (1 row)
 
-select * from T_pkey1 order by key1 using @<, key2;
+select * from T_pkey1 order by key1 using @<, key2 collate "C";
  key1 |         key2         |                   txt                    
 ------+----------------------+------------------------------------------
     1 | KEY1-3               | should work                             
@@ -174,7 +174,7 @@ select * from T_pkey1 order by key1 using @<, key2;
     2 | key2-9               | test key                                
 (6 rows)
 
-select * from T_pkey2 order by key1 using @<, key2;
+select * from T_pkey2 order by key1 using @<, key2 collate "C";
  key1 |         key2         |                   txt                    
 ------+----------------------+------------------------------------------
     1 | KEY1-3               | test key                                

src/pl/tcl/sql/pltcl_queries.sql

@@ -70,8 +70,8 @@ select tcl_sum(key1) from T_pkey1 where key1 = 99;
 select 1 @< 2;
 select 100 @< 4;
 
-select * from T_pkey1 order by key1 using @<, key2;
-select * from T_pkey2 order by key1 using @<, key2;
+select * from T_pkey1 order by key1 using @<, key2 collate "C";
+select * from T_pkey2 order by key1 using @<, key2 collate "C";
 
 -- show dump of trigger data
 insert into trigger_test values(1,'insert');