address comment

Signed-off-by: Andy Lok <[email protected]>

tests/common/mod.rs

@@ -24,11 +24,17 @@ const REGION_SPLIT_TIME_LIMIT: Duration = Duration::from_secs(15);
 
 // Delete all entries in TiKV to leave a clean space for following tests.
 pub async fn clear_tikv() {
+    // DEFAULT_REGION_BACKOFF is not long enough for CI environment. So set a longer backoff.
+    let backoff = tikv_client::Backoff::no_jitter_backoff(100, 30000, 20);
     let raw_client =
         RawClient::new_with_config(pd_addrs(), Config::default().with_default_keyspace())
             .await
             .unwrap();
-    raw_client.delete_range(..).await.unwrap();
+    raw_client
+        .with_backoff(backoff)
+        .delete_range(..)
+        .await
+        .unwrap();
 
     let txn_client =
         TransactionClient::new_with_config(pd_addrs(), Config::default().with_default_keyspace())