fix: revert default value for trie cache capacity (#7101)

Revert default value (to 50K) because after #7022 we got more evidence that it doesn't help to speed up storage ops.

## Testing

Existing tests.

core/store/src/config.rs

@@ -97,7 +97,7 @@ impl Default for StoreConfig {
             // we use it since then.
             block_size: bytesize::ByteSize::kib(16),
 
-            trie_cache_capacities: vec![(ShardUId { version: 1, shard_id: 3 }, 2_000_000)],
+            trie_cache_capacities: Default::default(),
         }
     }
 }