Add database roles used in testsuite

Actually only "tileuser" is currently used, but
"development_cartodb_user_3" is also referenced by the gadm4.sql
so I added that too.

test/sql/windshaft.test.sql

@@ -15,6 +15,8 @@ SET search_path = public, pg_catalog;
 SET default_tablespace = '';
 SET default_with_oids = false;
 
+-- tileuser role
+CREATE USER tileuser;
 
 -- first table
 CREATE TABLE test_table (