net-p2p/go-ethereum: Update to 1.9.0

• Remove no longer required patch "fdlimit_freebsd.go" as those changes have been merged by upstream.
• Add a pkg-message to give users some advice when upgrading from releases lower than 1.9.0. [1]

Changelog:

https://github.com/ethereum/go-ethereum/releases/tag/v1.9.0

PR: 239111
Submitted by: Enrique Fynn <me@enriquefynn.com> (maintainer)
Approved by: Enrique Fynn (maintainer) [1]