More fixes for display-comint-buffer-action

More fixes for display-comint-buffer-action

* lisp/window.el (display-comint-buffer-action):
Use display-buffer--same-window-action as the default value.

* lisp/progmodes/sh-script.el (sh-show-shell):
* lisp/shell.el (shell): Add display-comint-buffer-action to pop-to-buffer.

* lisp/progmodes/project.el (project-shell, project-eshell): Use
`bound-and-true-p display-comint-buffer-action' for backward-compatibility.

https://lists.gnu.org/archive/html/emacs-devel/2021-12/msg02964.html