NEWS: pre-announce removal of /run/boot-loader-entries/ support in lo… (#41622)

…gind

logind could read UAPI.1 Boot Loader Spec entries from
/run/boot-loader-entries/ in addition to ESP/XBOOTLDR. This was pretty
half-assed, and to my knowledge was never actually used much.

Let's remove support for it and simplify our codebase.

Let's schedule it for removal via NEWS in a future version, to give
people a chance to speak up.