PR #58592 re-added the so-called leak check.

Re-adding the leak-check masked a number of bugs, where you need to use -Z no-leak-check to observe them again.

We plan to eventually re-remove the leak check. But before doing so, we need to double-check that all of the aforementioned masked bugs are either fixed, or at the very least revisited in terms of determining their priority in a leak-check-free world.