scripted-diff: shorten BLOCK_SERIALIZATION_HEADER_SIZE constant

Renames the constant to be less verbose and better reflect its purpose:
it represents the size of the storage header that precedes serialized block data on disk,
not to be confused with a block's own header.

-BEGIN VERIFY SCRIPT-
git grep -q "STORAGE_HEADER_BYTES" $(git ls-files) && echo "Error: Target name STORAGE_HEADER_BYTES already exists in the codebase" && exit 1
sed -i 's/BLOCK_SERIALIZATION_HEADER_SIZE/STORAGE_HEADER_BYTES/g' $(git grep -l 'BLOCK_SERIALIZATION_HEADER_SIZE')
-END VERIFY SCRIPT-

src/node/blockstorage.h

@@ -75,10 +75,10 @@ static const unsigned int UNDOFILE_CHUNK_SIZE = 0x100000; // 1 MiB
 static const unsigned int MAX_BLOCKFILE_SIZE = 0x8000000; // 128 MiB
 
 /** Size of header written by WriteBlock before a serialized CBlock (8 bytes) */
-static constexpr size_t BLOCK_SERIALIZATION_HEADER_SIZE{std::tuple_size_v<MessageStartChars> + sizeof(unsigned int)};
+static constexpr size_t STORAGE_HEADER_BYTES{std::tuple_size_v<MessageStartChars> + sizeof(unsigned int)};
 
 /** Total overhead when writing undo data: header (8 bytes) plus checksum (32 bytes) */
-static constexpr size_t UNDO_DATA_DISK_OVERHEAD{BLOCK_SERIALIZATION_HEADER_SIZE + uint256::size()};
+static constexpr size_t UNDO_DATA_DISK_OVERHEAD{STORAGE_HEADER_BYTES + uint256::size()};
 
 // Because validation code takes pointers to the map's CBlockIndex objects, if
 // we ever switch to another associative container, we need to either use a
@@ -164,7 +164,7 @@ private:
      * blockfile info, and checks if there is enough disk space to save the block.
      *
      * The nAddSize argument passed to this function should include not just the size of the serialized CBlock, but also the size of
-     * separator fields (BLOCK_SERIALIZATION_HEADER_SIZE).
+     * separator fields (STORAGE_HEADER_BYTES).
      */
     [[nodiscard]] FlatFilePos FindNextBlockPos(unsigned int nAddSize, unsigned int nHeight, uint64_t nTime);
     [[nodiscard]] bool FlushChainstateBlockFile(int tip_height);