patch 8.2.4802: test is not cleaned up

Problem:    Test is not cleaned up.
Solution:   Make test clean up after itself.  Avoid NUL. (closes #10233)

src/testdir/test_autocmd.vim

@@ -3004,6 +3004,8 @@ func Test_autocmd_quit_psearch()
   augroup aucmd_win_test
     au!
   augroup END
+  new
+  pclose
 endfunc
 
 " Fuzzer found some strange combination that caused a crash.
@@ -3037,12 +3039,10 @@ func Test_autocmd_closing_cmdwin()
 endfunc
 
 func Test_autocmd_vimgrep()
-  %bwipe!
   augroup aucmd_vimgrep
     au QuickfixCmdPre,BufNew,BufReadCmd * sb
-    au QuickfixCmdPre,BufNew,BufReadCmd * q9
+    au QuickfixCmdPre,BufNew,BufReadCmd * q9
   augroup END
-  %bwipe!
   call assert_fails('lv ?a? foo', 'E926:')
 
   augroup aucmd_vimgrep

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4802,
 /**/
     4801,
 /**/