kernel: Move non-kernel db cache size constants

These have nothing to do with the txdb, so move them out and into the
node caches.

src/node/caches.cpp

@@ -12,17 +12,23 @@
 #include <algorithm>
 #include <string>
 
+// Unlike for the UTXO database, for the txindex scenario the leveldb cache make
+// a meaningful difference: https://github.com/bitcoin/bitcoin/pull/8273#issuecomment-229601991
+static constexpr int64_t MAX_TX_INDEX_CACHE{1024};
+//! Max memory allocated to all block filter index caches combined in MiB.
+static constexpr int64_t MAX_FILTER_INDEX_CACHE{1024};
+
 namespace node {
 std::tuple<IndexCacheSizes, kernel::CacheSizes> CalculateCacheSizes(const ArgsManager& args, size_t n_indexes)
 {
     int64_t nTotalCache = (args.GetIntArg("-dbcache", nDefaultDbCache) << 20);
     nTotalCache = std::max(nTotalCache, nMinDbCache << 20); // total cache cannot be less than nMinDbCache
     IndexCacheSizes sizes;
-    sizes.tx_index = std::min(nTotalCache / 8, args.GetBoolArg("-txindex", DEFAULT_TXINDEX) ? nMaxTxIndexCache << 20 : 0);
+    sizes.tx_index = std::min(nTotalCache / 8, args.GetBoolArg("-txindex", DEFAULT_TXINDEX) ? MAX_TX_INDEX_CACHE << 20 : 0);
     nTotalCache -= sizes.tx_index;
     sizes.filter_index = 0;
     if (n_indexes > 0) {
-        int64_t max_cache = std::min(nTotalCache / 8, max_filter_index_cache << 20);
+        int64_t max_cache = std::min(nTotalCache / 8, MAX_FILTER_INDEX_CACHE << 20);
         sizes.filter_index = max_cache / n_indexes;
         nTotalCache -= sizes.filter_index * n_indexes;
     }

src/txdb.h

@@ -29,11 +29,6 @@ static const int64_t nDefaultDbBatchSize = 16 << 20;
 static const int64_t nMinDbCache = 4;
 //! Max memory allocated to block tree DB specific cache
 static const int64_t nMaxBlockDBCache = 2;
-// Unlike for the UTXO database, for the txindex scenario the leveldb cache make
-// a meaningful difference: https://github.com/bitcoin/bitcoin/pull/8273#issuecomment-229601991
-static const int64_t nMaxTxIndexCache = 1024;
-//! Max memory allocated to all block filter index caches combined in MiB.
-static const int64_t max_filter_index_cache = 1024;
 //! Max memory allocated to coin DB specific cache (MiB)
 static const int64_t nMaxCoinsDBCache = 8;