vtkXMLDataParser: track `AppendedData` state explicitly
Bug-Debian: https://bugs.debian.org/
1064762
Origin: upstream,https://gitlab.kitware.com/vtk/vtk/-/commit/
3efa07ad277efe5c1d11a2ef2b907c095f68bbef
Forwarded: not-needed
Newer `libexpat` doesn't like being given the appended data after the
artificially ended document anymore. Avoid pushing it through to its
parser.
Gbp-Pq: Name 09_newer_expat.patch