osk-layouts: Drop comma key from de-extended and at-extended layouts

osk-layouts: Drop comma key from de-extended and at-extended layouts

The row containing that key was one key too long, which was causing
misalignment. The comma key is not shown in the us-extended layout
either and is available via long press on the dot key or via ?123,
making it the best candidate to remove from these layouts.

Closes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/8756
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3940>
(cherry picked from commit f076b775bbbe1f73307311c3c971ca8a12e67bf3)