Change default tab_label_length from 99999 to 1000

The whole value 99999 doesn't fit into the entry which looks ugly and,
to me, somehow a rounded value like 1000 (which is still sufficient
in terms of "unlimited" number of characters in a tab) looks more pleasing.

src/ui_utils.c

@@ -2394,7 +2394,7 @@ void ui_init_prefs(void)
 	stash_group_add_boolean(group, &interface_prefs.warn_on_project_close,
 		"warn_on_project_close", TRUE);
 	stash_group_add_spin_button_integer(group, &interface_prefs.tab_label_len,
-		"tab_label_length", 99999, "spin_tab_label_len");
+		"tab_label_length", 1000, "spin_tab_label_len");
 }