Remove dsQueryBatch in favor of ds.Batcher.

appengine/datastorecache/cache.go

Index: appengine/datastorecache/cache.go
diff --git a/appengine/datastorecache/cache.go b/appengine/datastorecache/cache.go
index b928686997fba7ecc5149bd3e7d473e567349ab3..92d68051be022973f151230d62df89737c4918b5 100644
--- a/appengine/datastorecache/cache.go
+++ b/appengine/datastorecache/cache.go
@@ -17,6 +17,7 @@ import (
 	"github.com/luci/luci-go/common/retry"
 	"github.com/luci/luci-go/server/router"
 
+	"github.com/luci/gae/impl/prod/constraints"
 	"github.com/luci/gae/service/datastore"
 	"github.com/luci/gae/service/info"
 
@@ -175,7 +176,7 @@ func (cache *Cache) pruneInterval() time.Duration {
 func (cache *Cache) manager() *manager {
 	return &manager{
 		cache:          cache,
-		queryBatchSize: managerQueryBatchSize,
+		queryBatchSize: constraints.DS().QueryBatchSize,
 	}
 }