Remove extra message-set-auto-save-file-name call in Gnus drafts

Bug#70579

* lisp/gnus/gnus-draft.el (gnus-draft-setup): This function is already
being called as part of the message-mail -> message-mode call
above. Running it twice results in a jump in assigned article numbers,
and the corresponding active value of the drafts group.

lisp/gnus/gnus-draft.el

@@ -262,8 +262,7 @@ If DONT-POP is nil, display the buffer after setting it up."
             (setq ga
                   (message-fetch-field gnus-draft-meta-information-header)))
           (insert mail-header-separator)
-          (forward-line 1)
-          (message-set-auto-save-file-name))))
+          (forward-line 1))))
     (gnus-backlog-remove-article group narticle)
     (when (and ga
                (ignore-errors (setq ga (car (read-from-string ga)))))