Flush memcached whenever we drop the databases.

This fixes some issues that we've had where commands will fail is
confusing ways after the database is rebuilt because data from before
the database was dropped is still in the memcached cache.

scripts/setup/postgres-init-db

@@ -15,5 +15,7 @@ CREATE SCHEMA zulip AUTHORIZATION zulip;
 CREATE EXTENSION tsearch_extras SCHEMA zulip;
 EOF
 
+sh "$(dirname "$0")/flush-memcached"
+
 echo "Database created"