Convert long array syntax in comments starting with "//"

I've verified the commit: use short array syntax using git grep to find matches, and everything seems to be fine.

I've reviewed the commit and also clone the branch locally to launch the grep command as follow:

git grep -r "\barray(" * | grep -F \/\/ | grep -v "vendor" | grep -v "node_modules" | awk '{print NR ": " $0}'
1: core/modules/migrate_drupal/tests/fixtures/drupal6.php:  'source' => "return array(\n  0 => array(@columns),\n  // You'll usually want to stop here. Provide more values\n  // if you want your 'default value' to be multi-valued:\n  1 => array(@columns),\n  2 => ...\n);",
2: core/modules/migrate_drupal/tests/fixtures/drupal6.php:  'translation' => "return array(\n  0 => array(@columns),\n  // Vous voudrez vous arrêter là dans la plupart des cas. Fournir plus de valeurs\n  // si vous souhaitez que votre 'valeur par défaut' ait des valeurs multiples :\n  1 => array(@columns),\n  2 => ...\n);",

I adjusted the git grep command to display the results line by line.

We can see that we still have 'array( ... ' but it's not in a comment as asked in the description of this issue.

Everything looks fine.

Committed/pushed to 11.x, thanks!