Sets up a MutationObserver to monitor when a specific DOM element (e.g., a div container)
is removed from the document. When the element is removed, it triggers a cleanup callback
and disconnects the observer to prevent memory leaks.
Parameters
key: string
A unique identifier for the element, used to manage observer references.
element: HTMLElement
The DOM element to monitor for removal from the DOM tree.
Sets up a MutationObserver to monitor when a specific DOM element (e.g., a div container) is removed from the document. When the element is removed, it triggers a cleanup callback and disconnects the observer to prevent memory leaks.