Suppress Axivion warnings about signal overrides

Both the colorChanged and the markerSizeChanged signals are already
present in the QXYSeries base class and are shadowed by the duplicate
definitions in QScatterSeries, which Axivion warns about.

We can't remove the QScatterSeries signals in Qt 6 as it would remove
public symbols from the ABI, but we can suppress the warning, and flag
these signals for removal in Qt 7.

Axivion-Id: qt_Add-ons_qtcharts_dev_linux:SV540
Axivion-Id: qt_Add-ons_qtcharts_dev_linux:SV541
Fixes: QTBUG-146050
Pick-to: 6.12
Change-Id: I7810474b8871b14aecc18f6d19aa4976ef8c579c
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
Reviewed-by: Sami Varanka <sami.varanka@qt.io>