doc: remove For ... comments

We don't add or maintain these, and they are of little value, as
well as having the effect of polluting diffs.

They are also wrong, i.e DEFAULT_SCRIPTCHECK_THREADS is not in
validation.h.

src/wallet/migrate.cpp

@@ -1,15 +1,20 @@
+// Copyright (c) 2024-present The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <compat/byteswap.h>
-#include <crypto/common.h> // For ReadBE32
+#include <crypto/common.h>
 #include <logging.h>
 #include <streams.h>
 #include <util/translation.h>
 #include <wallet/migrate.h>
 
+#include <array>
+#include <cstddef>
 #include <optional>
+#include <stdexcept>
 #include <variant>
+#include <vector>
 
 namespace wallet {
 // Magic bytes in both endianness's