feat(terminal)!: make 'belloff' and 'visualbell' apply to terminal bell (#30859)

vim-patch:8.2.4744: a terminal window can't use the bell
vim-patch:8.2.4745: using wrong flag for using bell in the terminal

BREAKING CHANGE: Bells from :terminal are now silent by default, unless
'belloff' option doesn't contain "term" or "all".

src/nvim/terminal.c

@@ -1178,9 +1178,10 @@ static int term_settermprop(VTermProp prop, VTermValue *val, void *data)
   return 1;
 }
 
+/// Called when the terminal wants to ring the system bell.
 static int term_bell(void *data)
 {
-  ui_call_bell();
+  vim_beep(BO_TERM);
   return 1;
 }