Replace more uses of wxFileName::Normalize() with MakeAbsolute()

Unlike the parent commit, this one does change the behaviour by not
applying some normalizations any more, but these changes are correct,
i.e. we really don't need to call Normalize(), which expands environment
variables in the file names by default, here and just want to make the
file paths absolute.

In particular, this fixes the problem of mangling file names containing
dollar signs in wxFileSystemWatcher.

Closes #19214.

samples/stc/stctest.cpp

@@ -601,7 +601,7 @@ void AppFrame::CreateMenu ()
 
 void AppFrame::FileOpen (wxString fname)
 {
-    wxFileName w(fname); w.Normalize(); fname = w.GetFullPath();
+    wxFileName w(fname); w.MakeAbsolute(); fname = w.GetFullPath();
     m_edit->LoadFile (fname);
     m_edit->SelectNone();
 }