Drop a misplaced \iow_shipout_x:Nn entry in l3obsoletes.txt

It was wrongly added to the list of removed functions, in commit
539a437 (Switch from x- to e-type in l3file, 2023-09-26).

Date (2022-09-27) in entries of the same function in list of deprecated
functions is changed to 2022-09-17, the one originally used in commit 539a437.

l3kernel/doc/l3obsolete.txt

@@ -31,10 +31,10 @@ Function                            Date deprecated
 \char_to_utfviii_bytes:n                 2022-10-09
 \char_to_nfd:N                           2022-10-09
 \cs_argument_spec:N                      2022-06-24
-\iow_shipout_x:cn                        2023-09-27
-\iow_shipout_x:cx                        2023-09-27
-\iow_shipout_x:Nn                        2023-09-27
-\iow_shipout_x:Nx                        2023-09-27
+\iow_shipout_x:cn                        2023-09-17
+\iow_shipout_x:cx                        2023-09-17
+\iow_shipout_x:Nn                        2023-09-17
+\iow_shipout_x:Nx                        2023-09-17
 \l_keys_key_tl                           2020-02-08
 \l_keys_path_tl                          2020-02-08
 \l_text_accents_tl                       2023-02-07
@@ -364,7 +364,6 @@ Function                                      Date removed
 \iow_now_when_avail:Nn                          2012-06-05
 \iow_now_when_avail:Nx                          2012-06-05
 \iow_open_streams:                              2011-09-08
-\iow_shipout_x:Nn                               2023-09-17
 \iow_wrap:xnnnN                                 2013-01-08
 \KV_process_no_space_removal_no_sanitize:NNn    2011-09-08
 \KV_process_space_removal_no_sanitize:NNn       2011-09-08