Rationales from the PR discussion:
> Currently we serialize the local time when connecting to outbound connections and the "adjusted network" time when someone connects to us. I presume the reason is to avoid a fingerprint in case the local time is misconfigured. However, the fingerprint still exists... I think using GetAdjustedTime here gives a false sense of security. It will be better for node operators to instead set the correct time.
> The timestamp a node sends to their inbounds will influence their adjusted time, and I think it makes sense to use the local time for that - this also counteracts non-local phenomena, where a wrong Adjusted Time is passed from A to B, affects B's adjusted time and is passed along to B's future peers and so on.
> This change makes the code simpler.
This is a backport of core#23695
Depends on D13357