test: preserve pre-flip pushdown_filters=false for tests asserting FilterExec-above-scan plans

Three tests captured their expected plans / metrics with pushdown_filters=false
default. After flipping that default to true they need to explicitly set the
option back for their scope:

- parquet::filter_pushdown::predicate_cache_default: config the SessionContext
  with pushdown_filters=false so the cache-usage assertion (0/0) still holds
- sqllogictest/clickbench.slt: SET pushdown_filters=false around the whole
  file (RESET at end) so ClickBench EXPLAIN plans stay intact
- sqllogictest/dynamic_filter_pushdown_config.slt: SET pushdown_filters=false
  for the default section at the top; the file already SETs true later for
  the second half — pair it with a RESET at the tail

Author: zhuqi-lucas

datafusion/core/tests/parquet/filter_pushdown.rs

@@ -619,8 +619,12 @@ fn get_value(metrics: &MetricsSet, metric_name: &str) -> usize {
 
 #[tokio::test]
 async fn predicate_cache_default() -> datafusion_common::Result<()> {
-    let ctx = SessionContext::new();
-    // The cache is on by default, but not used unless filter pushdown is enabled
+    // Verify the cache is not used when filter pushdown is off.
+    // `pushdown_filters` defaults to `true` since DataFusion 55, so
+    // disable it explicitly to exercise the "no pushdown" path.
+    let mut config = SessionConfig::new();
+    config.options_mut().execution.parquet.pushdown_filters = false;
+    let ctx = SessionContext::new_with_config(config);
     PredicateCacheTest {
         expected_inner_records: 0,
         expected_records: 0,

datafusion/sqllogictest/test_files/clickbench.slt

@@ -24,6 +24,12 @@
 # Data file made with DuckDB:
 # COPY (SELECT * FROM 'hits.parquet' LIMIT 10) TO 'clickbench_hits_10.parquet' (FORMAT PARQUET);
 
+# The EXPLAIN plans in this file were captured with pushdown_filters=false.
+# DataFusion 55 flips that default to true; disable it here to keep the plans
+# meaningful (filter kept above the scan) rather than absorbed into the scan.
+statement ok
+set datafusion.execution.parquet.pushdown_filters = false;
+
 statement ok
 CREATE EXTERNAL TABLE hits_raw
 STORED AS PARQUET
@@ -1238,3 +1244,6 @@ drop view hits;
 
 statement ok
 drop table hits_raw;
+
+statement ok
+reset datafusion.execution.parquet.pushdown_filters;

datafusion/sqllogictest/test_files/dynamic_filter_pushdown_config.slt

@@ -21,6 +21,12 @@
 # - enable_aggregate_dynamic_filter_pushdown (for Aggregate dynamic filters)
 # - enable_dynamic_filter_pushdown (controls all three)
 
+# The EXPLAIN plans in the "default" section below expect
+# pushdown_filters=false so the dynamic FilterExec stays above the scan.
+# DataFusion 55 flipped that default to true; explicitly disable it here.
+statement ok
+set datafusion.execution.parquet.pushdown_filters = false;
+
 # Setup: Create parquet test files
 statement ok
 CREATE TABLE test_data(id INT, value INT, name VARCHAR) AS VALUES
@@ -879,3 +885,6 @@ RESET datafusion.execution.parquet.max_row_group_size;
 
 statement ok
 RESET datafusion.execution.parquet.pushdown_filter_mode;
+
+statement ok
+RESET datafusion.execution.parquet.pushdown_filters;