bench: Reorg benchmarks without mempool removal
Summary:
This adds two additional re-orgs tests that clear the mempool after disconnecting blocks. This removes the need to remove them from the mempool during re-connect. As of writing this test, removing transactions from mempool during re-connect takes significant amount of time. Now we can see how much time.
Port of bchn#1077.
Depends on D13105.
Test Plan:
ninja bench-bitcoin
Reviewers: #bitcoin_abc, sdulfari
Reviewed By: #bitcoin_abc, sdulfari
Differential Revision: https://reviews.bitcoinabc.org/D13106