test_utils: scan the empty prefix in run_reads

Align run_reads with `main`: iterate prefixes of length 0..=len (was
1..=len) so the empty-prefix scan is exercised. This covers
`find_keys_by_prefix(&[])` against the exclusive ScyllaDB store, which
must not surface the timestamp sentinel row.

Author: Mathieu Baudet

linera-views/src/test_utils/mod.rs

@@ -176,7 +176,7 @@ pub async fn run_reads<S: KeyValueStore>(store: S, key_values: Vec<(Vec<u8>, Vec
     store.write_batch(batch).await.unwrap();
     for key_prefix in keys
         .iter()
-        .flat_map(|key| (0..key.len()).map(|u| &key[..=u]))
+        .flat_map(|key| (0..=key.len()).map(|u| &key[..u]))
     {
         // Getting the find_keys_by_prefix / find_key_values_by_prefix
         let len_prefix = key_prefix.len();