[Spreadsheet] Replace override cursor with QGraphicsItem::setCursor (#22097)

* [Spreadsheet] Replace the risky use of override cursor with
QGraphicsItem::setCursor

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/Mod/Spreadsheet/Gui/ZoomableView.cpp

@@ -122,6 +122,18 @@ ZoomableView::ZoomableView(Ui::Sheet* ui)
     });
 
     resetZoom();
+
+    auto connectCursorChangedSignal = [this](QHeaderView* hv) {
+        auto header = qobject_cast<SpreadsheetGui::SheetViewHeader*>(hv);
+        connect(header,
+                &SpreadsheetGui::SheetViewHeader::cursorChanged,
+                this,
+                [this](const QCursor& newerCursor) {
+                    qpw->setCursor(newerCursor);
+                });
+    };
+    connectCursorChangedSignal(stv->horizontalHeader());
+    connectCursorChangedSignal(stv->verticalHeader());
 }
 
 int ZoomableView::zoomLevel() const