`CollapseCombinedPath` was introduced by commit 551d3343 (cmDependsC:
Collapse relative include paths, 2013-06-19, v2.8.12~237^2) where the
existing `CollapseFullPath` should have been used instead.  Then its use
proliferated slightly.  Since `CollapseCombinedPath` is less widely used
and less robust (see issue #19049), use `CollapseFullPath` everywhere
instead.

Issue: #19050