Remove duplicate news entry for #11547

#11547 was backported to pip 22.3.1, so has already been released and already has a news entry:
https://pip.pypa.io/en/latest/news/#v22-3-1

As such, one shouldn't be included for it, for the next pip release:
https://pip.pypa.io/en/latest/news/#not-yet-released-2022-12-19

Author: edmorley