fa74d3d720 qa: Remove unused deserialization code in msg_version (MarcoFalke)
fa5099ceb7 p2p: Remove dead code for nVersion=10300 (MarcoFalke)
Pull request description:
This code is undocumented and confusing as well as dead, since peers with a version that old are disconnected immediately.
Backport of Core PR14025
Also removed relevant obsolete code from seeder.
Reviewer note: the net_processing changes we made in D333