FIX: In [DELETE] /admin/user/:id.json, parse boolean block_* parameter correctly (#17201)

When calling the API to delete a user:

```
curl -X DELETE "https://discourse.example.com/admin/users/159.json" \
-H "Content-Type: multipart/form-data;" \
-H "Api-Key: ***" \
-H "Api-Username: ***" \
-F "delete_posts=true" \
-F "block_email=false" \
-F "block_urls=false" \
-F "block_ip=false"
```

Setting the parameters `block_email`, `block_urls` and `block_ip`explicitly to `false` did not work because the values weren't being parsed to boolean.

app/controllers/admin/users_controller.rb

@@ -410,8 +410,10 @@ class Admin::UsersController < Admin::AdminController
     user = User.find_by(id: params[:id].to_i)
     guardian.ensure_can_delete_user!(user)
 
-    options = params.slice(:block_email, :block_urls, :block_ip, :context, :delete_as_spammer)
-    options[:delete_posts] = ActiveModel::Type::Boolean.new.cast(params[:delete_posts])
+    options = params.slice(:context, :delete_as_spammer)
+    [:delete_posts, :block_email, :block_urls, :block_ip].each do |param_name|
+      options[param_name] = ActiveModel::Type::Boolean.new.cast(params[param_name])
+    end
     options[:prepare_for_destroy] = true
 
     hijack do