refactor: setup app domains in the post-create hook

This is more consistent with app setup, at the cost of making it so developers must disable domains manually afterwards.

docs/appendices/0.29.0-migration-guide.md

@@ -12,3 +12,4 @@
 
 - The `DOKKU_WAIT_TO_RETIRE` environment variable has been migrated to a `checks` property named `wait-to-retire` and will be ignored if set as an environment variable.
 - The `Procfile` is now extracted when source code is extracted for a build and not from the built image. Users can specify alternative paths via the `procfile-path` property of the `ps` plugin. See the [process management documentation](/docs/processes/process-management.md#changing-the-procfile-location) for more information on how to configure the `Procfile` path for your application.
+- The `domains-setup` trigger has been removed. Initial app domains will now be automatically setup during app creation.

docs/development/plugin-triggers.md

@@ -713,21 +713,6 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 # TODO
 ```
 
-### `domains-setup`
-
-- Description: Initializes domains for an app if enabled
-- Invoked by:
-- Arguments: `$APP`
-- Example:
-
-```shell
-#!/usr/bin/env bash
-
-set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
-
-# TODO
-```
-
 ### `domains-vhost-enabled`
 
 - Description: Checks if a virtual hosts are enabled for an app