speed up range list generation from multi marks, fdo#75486 related

Change-Id: Id2114652948d12c92b0e7be7afa304bfffc8fbe0
speed up simple range list joins that could be appends, fdo#75486 related

Change-Id: I734ff88bc4c0633875c9e9c19a817b8b08511c83
remove duplicated call to mpChildrenShapes->SelectionChanged()

Found when investigating performance bottlenecks of fdo#75486, after the
selection is completed ScTabViewObj::getSelection() is called multiple
times, each creating a ScCellRangesObj of the range list of filtered
ranges, which then is used for
ScChildrenShapes::FindSelectedShapesChanges()

The duplicated call was introduced with
b41332475783c31136673fb44cf4c411bb0148f8
but IMHO does not make any sense at all unless it has obscure side
effects, it only slows down things even more.

Change-Id: I3cee2e3e62c24ad72efb8cc2021e74d0afc70b69