scale the cache change down a bit

src/txdb.h

@@ -26,7 +26,7 @@ struct CDiskTxPos;
 //! No need to periodic flush if at least this much space still available.
 static constexpr int MAX_BLOCK_COINSDB_USAGE = 10;
 //! -dbcache default (MiB)
-static const int64_t nDefaultDbCache = 640;
+static const int64_t nDefaultDbCache = 560;
 //! -dbbatchsize default (bytes)
 static const int64_t nDefaultDbBatchSize = 16 << 20;
 //! max. -dbcache (MiB)
@@ -40,7 +40,7 @@ static const int64_t nMaxBlockDBCache = 16;
 // a meaningful difference: https://github.com/bitcoin/bitcoin/pull/8273#issuecomment-229601991
 static const int64_t nMaxTxIndexCache = 1024;
 //! Max memory allocated to coin DB specific cache (MiB)
-static const int64_t nMaxCoinsDBCache = 128;
+static const int64_t nMaxCoinsDBCache = 32;
 
 /** CCoinsView backed by the coin database (chainstate/) */
 class CCoinsViewDB final : public CCoinsView