prod_settings_template: Extract more sections from "miscellaneous".
prod_settings_template: Extract more sections from "miscellaneous".

This finds three sets of related settings to extract from the
"Miscellaneous" settings section:
 - Service configuration (PostgreSQL, RabbitMQ, Redis, Memcached)
 - Previews (image, URL, and Twitter)
 - Logging and error reporting

kou/zulip,zulip/zulip,andersk/zulip,hackerkid/zulip,punchagan/zulip,eeshangarg/zulip,andersk/zulip,hackerkid/zulip,rht/zulip,rht/zulip,punchagan/zulip,kou/zulip,kou/zulip,punchagan/zulip,zulip/zulip,kou/zulip,rht/zulip,andersk/zulip,zulip/zulip,andersk/zulip,kou/zulip,eeshangarg/zulip,rht/zulip,hackerkid/zulip,hackerkid/zulip,hackerkid/zulip,zulip/zulip,eeshangarg/zulip,zulip/zulip,andersk/zulip,hackerkid/zulip,zulip/zulip,eeshangarg/zulip,andersk/zulip,rht/zulip,hackerkid/zulip,eeshangarg/zulip,punchagan/zulip,kou/zulip,punchagan/zulip,rht/zulip,eeshangarg/zulip,punchagan/zulip,andersk/zulip,punchagan/zulip,eeshangarg/zulip,zulip/zulip,kou/zulip,rht/zulip