Calculate new highest LeafVariant after delete #383
Description
When calculating the highest (still active [not deleted]) value, we determine highest and second highest priority LeafVariant and assume the secondHighest becomes active if the highest is marked for deletion.
This approach is overhauled since CS batches up modifications. This might lead to multiple intents being deleted in a single TransactionSet.
Hence, the logic here needs to change. Instead of determining the second highest, we need to determine the highest non deleted LeafVariant.
The logic in place as far as I can tell will remain the same as with the actual secondHighest entry.