consensus: temporarily skip scripts on big transactions (#1360)

Temporary workaround for #1350 until that issue is properly fixed.

zebra-consensus/src/script.rs

@@ -92,12 +92,19 @@ where
                     };
                     tracing::trace!(?utxo, "got UTXO");
 
+                    if transaction.inputs().len() < 20 {
                         zebra_script::is_valid(
                             transaction,
                             branch_id,
                             (input_index as u32, utxo.output),
                         )?;
                         tracing::trace!("script verification succeeded");
+                    } else {
+                        tracing::debug!(
+                            inputs.len = transaction.inputs().len(),
+                            "skipping verification of script with many inputs to avoid quadratic work until we fix zebra_script/zcash_script interface"
+                        );
+                    }
 
                     Ok(())
                 }