Drop postgres 9.6 specific setting from structure.sql

Closes #2404

.travis.yml

@@ -15,7 +15,7 @@ env:
   global:
     - OSM_MEMCACHE_SERVERS="127.0.0.1"
 before_script:
-  - sed -e "/idle_in_transaction_session_timeout/d" -e 's/ IMMUTABLE / /' -e "/^--/d" db/structure.sql > db/structure.expected
+  - sed -e 's/ IMMUTABLE / /' -e "/^--/d" db/structure.sql > db/structure.expected
   - psql -U postgres -c "CREATE DATABASE openstreetmap"
   - psql -U postgres -c "CREATE EXTENSION btree_gist" openstreetmap
   - psql -U postgres -f db/functions/functions.sql openstreetmap

db/structure.sql

@@ -1,6 +1,5 @@
 SET statement_timeout = 0;
 SET lock_timeout = 0;
-SET idle_in_transaction_session_timeout = 0;
 SET client_encoding = 'UTF8';
 SET standard_conforming_strings = on;
 SELECT pg_catalog.set_config('search_path', '', false);