To test the custom ancestor limit on node1 (passed by the argument
-limitancestorcount), we check for three conditions:-> the # of txs in the node1 mempool is equal to the the limit -> all txs in node1 mempool are a subset of txs in node0 mempool -> the node1 mempool txs match the start of the constructed tx-chain
This is a backport of Core PR17435