Fix stale QuadItem removal after mutable ClusterItem position updates

[Aparnamohan1312]

Summary

NonHierarchicalDistanceBasedAlgorithm.updateItem() may fail to remove the previously indexed QuadItem when a mutable ClusterItem changes position before calling updateItem().

Expected behavior

Calling updateItem() after modifying a ClusterItem's position should remove the previously indexed QuadItem from the PointQuadTree and reinsert the updated item, leaving only a single indexed entry.

Observed behavior

removeItem() reconstructs a new QuadItem using the current state of the ClusterItem.

Since QuadItem caches the projected point during construction, if the item's position has changed before updateItem() is called, the reconstructed QuadItem contains the updated coordinates instead of the coordinates used during insertion.

PointQuadTree.remove() navigates the tree using these updated coordinates and may fail to remove the originally indexed QuadItem, leaving a stale entry in the spatial index.

Environment details

1. Device: N/A (algorithm-level issue)
2. Android version: N/A
3. Library version: Current main branch (commit 0147954)

Steps to reproduce

1. Create a mutable implementation of ClusterItem.
2. Add the item to NonHierarchicalDistanceBasedAlgorithm.
3. Change the item's position.
4. Call updateItem(item).
5. Observe that removeItem() reconstructs a new QuadItem using the updated coordinates rather than the original indexed instance.

Code example

TestingItem item = new TestingItem("item", 0.1, 0.1);

NonHierarchicalDistanceBasedAlgorithm<ClusterItem> algo =
    new NonHierarchicalDistanceBasedAlgorithm<>();

algo.addItem(item);

// Position changes before update.
item.setPosition(0.8, 0.8);

algo.updateItem(item);

Stack trace

N/A (logical correctness issue; no exception is thrown).

[Aparnamohan1312]

PR - #1730