spanner/request-id: some methods like Cleanup do not do retries autom…

…atically

spanner/batch.go

@@ -134,8 +134,6 @@ func (t *BatchReadOnlyTransaction) PartitionReadUsingIndexWithOptions(ctx contex
 	}
 	var md metadata.MD
 	sh.updateLastUseTime()
-	// TODO: (@odeke-em) retrieve the requestID and increment the RPC number
-	// then send it along in every call per retry.
 	resp, err = client.PartitionRead(contextWithOutgoingMetadata(ctx, sh.getMetadata(), t.disableRouteToLeader), &sppb.PartitionReadRequest{
 		Session:          sid,
 		Transaction:      ts,
@@ -286,8 +284,6 @@ func (t *BatchReadOnlyTransaction) Cleanup(ctx context.Context) {
 	t.sh = nil
 	sid, client := sh.getID(), sh.getClient()
 
-	// TODO: (@odeke-em) retrieve the requestID and increment the RPC number
-	// then send it along in every call per retry.
 	var md metadata.MD
 	err := client.DeleteSession(contextWithOutgoingMetadata(ctx, sh.getMetadata(), true), &sppb.DeleteSessionRequest{Name: sid}, gax.WithGRPCOptions(grpc.Header(&md)))