clusterlin: avoid depgraph argument in SanityCheck (cleanup)

Since the deterministic ordering change, SpanningForestState holds a
reference to the DepGraph it is linearizing. So this means we do not
need to pass it to SanityCheck() as an argument anymore.

src/test/fuzz/cluster_linearize.cpp

@@ -919,7 +919,7 @@ FUZZ_TARGET(clusterlin_sfl)
         if (rng.randbits(4) == 0) {
             // Perform sanity checks from time to time (too computationally expensive to do after
             // every step).
-            sfl.SanityCheck(depgraph);
+            sfl.SanityCheck();
         }
         auto diagram = sfl.GetDiagram();
         if (rng.randbits(4) == 0) {