libsnapshot: snapuserd: Enable read-ahead functionality

This enables read-ahead functionality by having
scratch space in the COW

Bug: 183863613
Test: OTA tests with new COW format

Signed-off-by: Akilesh Kailash <akailash@google.com>
Change-Id: I7988687c81d0ea239e71695818199db4653ddb80
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
index 1192e7d..f43ea68 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
@@ -37,7 +37,7 @@
     // Number of CowOperations in a cluster. 0 for no clustering. Cannot be 1.
     uint32_t cluster_ops = 200;
 
-    bool scratch_space = false;
+    bool scratch_space = true;
 };
 
 // Interface for writing to a snapuserd COW. All operations are ordered; merges