regression from 6484ccb4,
can be seen for example in Writer's page preview mode, changing zoom
by a mouse wheel does not update the zoom slider.

these slot ids are sometimes collected into an array to pass to
SfxBindings::Invalidate(sal_uInt16*), which requires a _sorted_ array,
so let's not modify the values and break the sort order.

Change-Id: I9cb59a6eed2f19dfb3a308d7654d8b0b1779ae6b