[BUG] org-delete-indentation on region doesn't work when END is before BEGIN [9.6.1 (release_9.6.1-40-g3d817c @ /home/sbaugh/.local/src/emacs29/lisp/org/)]

[Spencer Baugh <sbaugh@janestreet.com>]

1. emacs -Q
2. Insert the following in an org-mode buffer
* head
a
b
3. C-x h M-^ and note that it's now formatted as:
a
b
 * head
4. Undo, then M-> C-SPC M-< C-n M-^ and note that it's now formatted as:
* head a
b
5. Undo, then M-< C-SPC M-> M-^ and note that it's now formatted
(correctly) as:
* head a b

The 3rd and 4th steps are wrong, or at least inconsistent with how
normal delete-indentation works on a region.  In 4, I assume the issue
is that org-delete-indentation doesn't check to see if a region is
active before using its special logic.  No idea what's up with 3.

Emacs  : GNU Emacs 29.0.60 (build 3, x86_64-pc-linux-gnu, X toolkit, cairo version 1.15.12, Xaw scroll bars)
 of 2023-03-13
Package: Org mode version 9.6.1 (release_9.6.1-40-g3d817c @ /home/sbaugh/.local/src/emacs29/lisp/org/)