Unify the LMDB limits in node and in cardano-tools

[jasagredo]

The LMDB limits are replicated in unstable-cardano-tools and in cardano-node, because we didn't want to impose limits on the node, but we need those to re-open the snapshots, so we copy-pasted the values from the node. But as Alex suggests here we could just upstream this into ouroboros-consensus.