clusterlin: minimize chunks (feature)

After the normal optimization process finishes, and finds an optimal
spanning forest, run a second process (while computation budget remains)
to split chunks into minimal equal-feerate chunks.

src/txgraph.cpp

@@ -2063,8 +2063,7 @@ std::pair<uint64_t, bool> GenericClusterImpl::Relinearize(TxGraphImpl& graph, in
     uint64_t rng_seed = graph.m_rng.rand64();
     auto [linearization, optimal, cost] = Linearize(m_depgraph, max_iters, rng_seed, m_linearization, /*is_topological=*/IsTopological());
     // Postlinearize to undo some of the non-determinism caused by randomizing the linearization.
-    // This also guarantees that all chunks are connected (which is not guaranteed by SFL
-    // currently, even when optimal).
+    // This also guarantees that all chunks are connected (even when non-optimal).
     PostLinearize(m_depgraph, linearization);
     // Update the linearization.
     m_linearization = std::move(linearization);