Auto merge of #132231 - lukas-code:rc-plug-leaks, r=tgross35

Rc/Arc: don't leak the allocation if drop panics

Currently, when the last `Rc<T>` or `Arc<T>` is dropped and the destructor of `T` panics, the allocation will be leaked. This leak is unnecessary since the data cannot be (safely) accessed again and `Box` already deallocates in this case, so let's do the same for `Rc` and `Arc`, too.

Author: bors