test: Add missing sync_blocks to feature_pruning

Author: MarcoFalke

test/functional/feature_pruning.py

@@ -204,6 +204,7 @@ def reorg_test(self):
         self.log.info("Mine 220 more large blocks so we have requisite history")
 
         mine_large_blocks(self.nodes[0], 220)
+        self.sync_blocks(self.nodes[0:3], timeout=120)
 
         usage = calc_usage(self.prunedir)
         self.log.info("Usage should be below target: %d" % usage)