This update has probably been paid by Intel, you normally don't work on optimizing a game for a specific hardware when you have announced the end of support.
It's possible, but CDPR have been very good about trying to update the game for various hardware over the years for various different companies, like adding SMT for AMD CPUs, or the update before this that added the latest version of FSR with frame gen.
Also this Arrow Lake boost doesn't seem to be the centrepiece of the update, but more of an added bonus they threw in; the rest of the update is stuff they teased before, like having Johnny appear in your car, and the ability to customise cars paintwork and "steal" patterns from any car you drive past on the street).
I will fully admit that I am biased towards CDPR after being a fan of theirs since 2009, but I'm too old and cynical to be a fanboy, so whilst I honestly believe that they optimised for Arrow Lake off their own backs without prompting from Intel (based on a history of this kind of optimisation and bug fixing they have done for various games over the years), I do agree that it is a possibility, though I do wonder if Intel would really pay CDPR to update a nearly 5 year old game to improve the FPS on it, rather than focusing their attention (and payments) for more recent games that might be experiencing the same issues.