Lightning not installed by blt drupal:install

[ba66e77]

Describe the bug
BLT docs say it installs Lightning by default but in practice I'm seeing the Standard profile installed instead. It looks like the configuration setting for project.profile.name is missing resulting in and empty string being passed to the drush site-install command and a PHP Notice, as seen below.

$ blt drupal:install
> internal:drupal:install
[Acquia\Blt\Robo\Tasks\DrushTask] Running /var/www/d9take6/vendor/bin/drush @self site-install '' install_configure_form.enable_update_status_module=NULL --sites-subdir=default --site-name --site-mail=no-reply@acquia.com --account-name=DFWBLKuBtD --account-mail=no-reply@acquia.com --locale=en -v --ansi in /var/www/d9take6/docroot
PHP Notice:  Uninitialized string offset: 0 in /var/www/d9take6/vendor/drush/drush/src/Preflight/ArgsPreprocessor.php on line 72

To Reproduce
Steps to reproduce the behavior, ideally starting from a fresh install of BLT:

1. Install BLT 12 via composer create-project acquia/drupal-recommended-project mysite
2. Invoke blt drupal:install either by setting up a local or triggering a CI tool build

Expected behavior
Lightning is installed

System information

• BLT version: 12.x

[danepowell]

Lightning is no longer added to the project or installed by default, that should be provided by the distribution. I think that's only mentioned on this page, which also warns that it shouldn't be used with BLT 12. Did you see it anywhere else?

But yeah, it shouldn't be throwing a notice.

[ba66e77]

No, that's the only page I found it on. I got BLT in by installing the acquia/drupal-recommended-project which is including in Lightning. The expectation then is that it should be telling BLT what profile to use?