Revert "Set hot_standby_feedback = 'on'"

This reverts commit 7ec447d.

Uncomfirmed, but this was possibly causing load issues on the master by
increasing table bloat.

Author: mwiencek

postgres-slave/postgresql.conf.ctmpl

@@ -5,7 +5,6 @@ default_statistics_target = '300'
 default_text_search_config = 'pg_catalog.english'
 effective_cache_size = '{{keyOrDefault "docker-server-configs/services/postgres-slave.json/effective_cache_size" "4GB"}}'
 hot_standby = 'on'
-hot_standby_feedback = 'on'
 lc_messages = 'en_US.UTF-8'
 lc_monetary = 'en_US.UTF-8'
 lc_numeric = 'en_US.UTF-8'