patch 8.2.4149: test override not restored, autocommand left behind

Problem:    Test override not restored, autocommand left behind.
Solution:   Correct restoring test override.  Delete autocommand afterwards.
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 1fc960f..1ecb883 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
Binary files differ