refactor: Use HashWriter over legacy CHashWriter (via SerializeHash)

src/init.cpp

@@ -1195,7 +1195,7 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
                 InitError(strprintf(_("Could not parse asmap file %s"), fs::quoted(fs::PathToString(asmap_path))));
                 return false;
             }
-            const uint256 asmap_version = SerializeHash(asmap);
+            const uint256 asmap_version = (HashWriter{} << asmap).GetHash();
             LogPrintf("Using asmap version %s for IP bucketing\n", asmap_version.ToString());
         } else {
             LogPrintf("Using /16 prefix for IP bucketing\n");

src/netgroup.cpp

@@ -11,7 +11,7 @@ uint256 NetGroupManager::GetAsmapChecksum() const
 {
     if (!m_asmap.size()) return {};
 
-    return SerializeHash(m_asmap);
+    return (HashWriter{} << m_asmap).GetHash();
 }
 
 std::vector<unsigned char> NetGroupManager::GetGroup(const CNetAddr& address) const