scripted-diff: Use blocks_path where possible

-BEGIN VERIFY SCRIPT-
  sed -i 's|].chain_path / "blocks"|].blocks_path|g' $(git grep -l chain_path)
-END VERIFY SCRIPT-

test/functional/feature_dirsymlinks.py

@@ -26,7 +26,7 @@ class SymlinkTest(BitcoinTestFramework):
         self.stop_node(0)
 
         rename_and_link(
-            from_name=self.nodes[0].chain_path / "blocks",
+            from_name=self.nodes[0].blocks_path,
             to_name=dir_new_blocks,
         )
         rename_and_link(