fix 'return false' from parse

this was abandoned early on the manger side  but seems like we left behind on plugin side.
more flexible extensions with yaml plugin
validate data correctly for yaml/constructed
fixed issue with only adding one child to keyed, the group only got the host that forced it's creation

fixes #31382
fixes #31365

lib/ansible/plugins/inventory/virtualbox.py

@@ -173,7 +173,7 @@ class InventoryModule(BaseInventoryPlugin):
 
         if not config_data or config_data.get('plugin') != self.NAME:
             # this is not my config file
-            return False
+            raise AnsibleParserError("Incorrect plugin name in file: %s" % config_data.get('plugin', 'none found'))
 
         source_data = None
         if cache and cache_key in inventory.cache: