patch 8.2.2169: Vim9: test leaves file behind

Problem:    Vim9: test leaves file behind.
Solution:   Rename script files. (Dominique Pellé, closes #7511)
            Use try/finally.
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 47ea43d..b0e7635 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -2412,7 +2412,7 @@
       'delcommand Echo',
       ])
   CheckScriptSuccess([
-      'vim9script'
+      'vim9script',
       'command Echo cd # comment',
       'Echo',
       'delcommand Echo',
@@ -2949,6 +2949,7 @@
   endif
   delete('Xsourced')
   delete('Xclose')
+  delete('Xdone')
 enddef