fix: import CacheAccessor trait for len() method in tests

Replace unused FileStatisticsCache import with CacheAccessor
which provides the len() method used in tests.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: adriangb

datafusion/core/src/datasource/listing_table_factory.rs

@@ -220,9 +220,8 @@ mod tests {
         datasource::file_format::csv::CsvFormat, execution::context::SessionContext,
         test_util::parquet_test_data,
     };
-    use datafusion_execution::cache::cache_manager::{
-        CacheManagerConfig, FileStatisticsCache,
-    };
+    use datafusion_execution::cache::cache_manager::CacheManagerConfig;
+    use datafusion_execution::cache::CacheAccessor;
     use datafusion_execution::cache::cache_unit::DefaultFileStatisticsCache;
     use datafusion_execution::config::SessionConfig;
     use datafusion_execution::runtime_env::RuntimeEnvBuilder;