patch 8.2.4157: terminal test fails because Windows sets the title

Problem:    Terminal test fails because Windows sets the title.
Solution:   Add the "vterm_title" testing override and use it in the test.
            (Ozaki Kiichi, closes #9556)
diff --git a/src/globals.h b/src/globals.h
index 94da8e0..7e0c1e5 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1642,6 +1642,7 @@
 EXTERN int  no_query_mouse_for_testing INIT(= FALSE);
 EXTERN int  ui_delay_for_testing INIT(= 0);
 EXTERN int  reset_term_props_on_termresponse INIT(= FALSE);
+EXTERN int  disable_vterm_title_for_testing INIT(= FALSE);
 EXTERN long override_sysinfo_uptime INIT(= -1);
 EXTERN int  override_autoload INIT(= FALSE);