Disable prepared statements in example database configs

config/database.yml.mysql

@@ -42,3 +42,4 @@ test: &test
   password:
   # host: localhost
   # socket: /tmp/mysql.sock
+  prepared_statements: false

config/database.yml.postgresql

@@ -50,3 +50,4 @@ test: &test
   username: postgres
   password:
   # host: localhost
+  prepared_statements: false