patch 8.2.5096: terminal test still fails with some shell commands

Problem:    Terminal test still fails with some shell commands.
Solution:   Add missing "call".  (closes #10530)
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index b64d5cf..d0f1438 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -1222,7 +1222,7 @@
   let buf = RunVimInTerminal('', {})
 
   " the shell may set the window title, we don't want that here
-  call term_sendkeys(buf, ":test_override('vterm_title', 1)\<CR>")
+  call term_sendkeys(buf, ":call test_override('vterm_title', 1)\<CR>")
 
   " Open a terminal window and wait for the prompt to appear
   call term_sendkeys(buf, ":term\<CR>")