Make `M-x run-python' select the window again

Interactively, we want M-x run-python to focus the interpreter buffer.
The previous code failed in two ways:

- the call to 'display-buffer' was not reached if an interpreter
  was already running,

- set-buffer is ineffectual if the interpreter's window is not
  selected: once Emacs returns to the command loop, the current buffer
  will revert back to what the selected window contains.

* lisp/progmodes/python.el (python-shell-make-comint): Handle the SHOW
argument regardless of whether an interpreter buffer exists, and use
pop-to-buffer to select the window.
(run-python): Delegate buffer management to
'python-shell-make-comint'.

* test/lisp/progmodes/python-tests.el
(python-tests--run-python-selects-window): Rename from
'python-tests--bug31398', and adjust assertions (bug#52380).

lisp/progmodes/python.el

@@ -2994,8 +2994,9 @@ killed."
                   (mapconcat #'identity args " ")))
             (with-current-buffer buffer
               (inferior-python-mode))
-            (when show (display-buffer buffer))
             (and internal (set-process-query-on-exit-flag process nil))))
+        (when show
+          (pop-to-buffer proc-buffer-name))
         proc-buffer-name))))
 
 ;;;###autoload
@@ -3027,7 +3028,6 @@ process buffer for a list of commands.)"
          (python-shell-make-comint
           (or cmd (python-shell-calculate-command))
           (python-shell-get-process-name dedicated) show)))
-    (set-buffer buffer)
     (get-buffer-process buffer)))
 
 (defun run-python-internal ()