fix(mito): avoid caching empty batches in row group (#4652)

* fix: avoid caching empty batches in row group

* fix: clippy

* Update tests/cases/standalone/common/select/last_value.sql

* fix: sqlness

src/mito2/src/read/last_row.rs

@@ -213,6 +213,10 @@ impl RowGroupLastRowReader {
     /// Updates row group's last row cache if cache manager is present.
     fn maybe_update_cache(&mut self) {
         if let Some(cache) = &self.cache_manager {
+            if self.yielded_batches.is_empty() {
+                // we always expect that row groups yields batches.
+                return;
+            }
             let value = Arc::new(SelectorResultValue {
                 result: std::mem::take(&mut self.yielded_batches),
                 projection: self