p2p: ProcessHeadersMessage(): fix received_new_header
p2p: ProcessHeadersMessage(): fix received_new_header

Follow-up to #25717. The commit "Utilize anti-DoS headers download
strategy" changed how this bool variable is computed, so that its value
is now the opposite of what it should be.

GitHub-Pull: #26172
Rebased-From: bdcafb913398f0cdaff9c880618f9ebfc85c7693

fujicoin/fujicoin,fujicoin/fujicoin,fujicoin/fujicoin,fujicoin/fujicoin,fujicoin/fujicoin,fujicoin/fujicoin