Fix a few contrib regression test scripts that hadn't gotten the word

about best practice for including the module creation scripts: to wit
that you should suppress NOTICE messages.  This avoids creating
regression failures by adding or removing comment lines in the module
scripts.

contrib/pg_trgm/sql/pg_trgm.sql

@@ -1,6 +1,12 @@
+--
+-- first, define the datatype.  Turn off echoing so that expected file
+-- does not depend on contents of pg_tgrm.sql.
+--
+SET client_min_messages = warning;
 \set ECHO none
 \i pg_trgm.sql
 \set ECHO all
+RESET client_min_messages;
 
 select show_trgm('');
 select show_trgm('(*&^$@%@');