vim-patch:9.0.1021: test trips over g:name

Problem:    Test trips over g:name.
Solution:   Delete g:name after using it.

d6e74f5479

Co-authored-by: Bram Moolenaar <Bram@vim.org>

test/old/testdir/runtest.vim

@@ -174,6 +174,7 @@ endfunc
 for name in s:GetSwapFileList()
   call delete(name)
 endfor
+unlet name
 
 
 " Invoked when a test takes too much time.