Bug 479861

SUMMARY
***
Dropping to a list when `canDropMimeData` returns _false_ results in `dropMimeData` being executed, when in normal circumstances it would only be run if canDropMimeData returned _true_.
***

PRE-REQUIREMENTS
1. Have a Qt Widgets app that displays a tree view.
2. The tree view's items must accept drops, and have drag enabled for convenience.
2. Use a model that inherits from `QAbstractItemModel` and implements `canDropMimeData` and `dropMimeData`.
3. The model should contain two or more items.
4. Despite the tree view being able to accept drops, the model must return _false_ for `canDropData`.

STEPS TO REPRODUCE
1. Drag one item from the list onto another item from the list.
or
1. Alternatively, drag a file from Dolphin into the list.

OBSERVED RESULT
On a Plasma (Wayland) session:
* `dropMimeData` is run after the item is dropped
On a Plasma (X11) session:
* `dropMimeData` is not run after the item is dropped

EXPECTED RESULT
In either session:
* `dropMimeData` is not run after the item is dropped

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora Linux 39, Linux 6.6.9-200.fc39.x86_64 (64 bits)
KDE Plasma Version: 6.0.80
KDE Frameworks Version: 5.249.0
Qt Version: 6.6.0
Graphics Platform: Wayland

ADDITIONAL INFORMATION
I thought this might be a bug in Qt, but it doesn't happen when running the same Qt app inside a Gnome (Wayland) session, it only affects Plasma (Wayland), hence why I'm reporting it here.