Renders the consumers' Slack templates and posts them, both with the
customer Slack bot's token. Goes through the customer publisher so a
permanently unreachable channel is tolerated rather than re-driving the
event.
The customer-facing post, to channels the caller already resolved and
cleared against the customer's preferences. A DISABLED template stops
it for every customer.
Renders the consumers' Slack templates and posts them, both with the customer Slack bot's token. Goes through the customer publisher so a permanently unreachable channel is tolerated rather than re-driving the event.