Avoid `switch-to-buffer` when launching multi-vterm

[karthink]

The usage of switch-to-buffer in the multi-vterm command makes the initial display of vterm ignore the user's display-buffer-alist customization.

To reproduce this, you can set:

(setq display-buffer-alist
'(("^\\*vterminal.*$" display-buffer-at-bottom)))

and run M-x multi-vterm.

Consider replacing it with pop-to-buffer-same-window, or let-binding switch-to-buffer-obey-display-actions around the switch-to-buffer call instead?