[bitcoin] Merged PR from laanwj (nostr:nprofile1qqsq4gu7tthengqq577mpdyezkxf90z25g8mvkf355ks2k67km0lwwqpzdmhxue69uhkummnw3ezu7psvchx7un8zn5kcn): net: Use actual memory size in receive buffer accounting https://github.com/bitcoin/bitcoin/pull/31164