patch 8.2.1938: wiping out a terminal buffer makes some tests fail

Problem:    Wiping out a terminal buffer makes some tests fail.
Solution:   Do not wipe out the terminal buffer unless wanted.
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index 829706c..f5b99bc 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -1230,7 +1230,7 @@
   call assert_fails("call term_dumpwrite(buf, '')", 'E482:')
   call assert_fails("call term_dumpwrite(buf, test_null_string())", 'E482:')
   call test_garbagecollect_now()
-  call StopVimInTerminal(buf)
+  call StopVimInTerminal(buf, 0)
   call TermWait(buf)
   call assert_fails("call term_dumpwrite(buf, 'Xtest.dump')", 'E958:')
   call assert_fails('call term_sendkeys([], ":q\<CR>")', 'E745:')