fix example and test compile errors

- Remove undefined lambdas_params variable from json_shredding.rs example
- Import Poll::Ready and Poll::Pending in coop.rs test (pre-existing missing import)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: LiaCastaneda

datafusion-examples/examples/data_io/json_shredding.rs

@@ -330,7 +330,6 @@ impl ShreddedJsonRewriter {
                 if let Some(column) = func.args()[1]
                     .as_any()
                     .downcast_ref::<expressions::Column>()
-                    .filter(|col| !lambdas_params.contains(col.name()))
                 {
                     let column_name = column.name();
                     // Check if there's a flat column with underscore prefix

datafusion/core/tests/execution/coop.rs

@@ -59,7 +59,7 @@ use std::error::Error;
 use std::fmt::Formatter;
 use std::ops::Range;
 use std::sync::Arc;
-use std::task::Poll;
+use std::task::Poll::{self, Pending, Ready};
 use std::time::Duration;
 use tokio::runtime::{Handle, Runtime};
 use tokio::select;