fix use-after-free in AddObserver

[grind086]

Objective

Fixes #22152

Solution

From the safety notes on DynamicBundle::apply_effect:

If any part of ptr is to be accessed in this function, it must not be dropped at any point in get_components.

The MovingPtr here is dropped when it goes out of scope, so the assume_init here is invalid. This is fixed by mem::forget-ing the pointer in get_components, which will leave the allocation intact for apply_effect.

Testing

Using the example from the issue, the logs are correct after this patch