#13666 introduced a footgun when using `toOwnedSlice` with `errdefer array_list.deinit()`, since `toOwnedSlice` could retain capacity if `resize` failed, meaning it would leak without `deinit` being called. This meant that the only correct way to use `toOwnedSlice` was with `defer` instead of `errdefer` to ensure that the ArrayList would get cleaned up.

Now, toOwnedSlice will now behave similarly to how it did before #13666, in that it will always clear the ArrayList's capacity if the resize/realloc succeeds.

This also reverts commit 05890a12f532ba9d58904a14381ec174b9efe473, which was contingent on the modified toOwnedSlice behavior.

Closes #13946