update_engine: temporary estimation solution

Use 4096 compression factor for estimation to oversize the cow, until we
have an accurate updated estimation algorithm working

Bug: 2928753
Test: th
Change-Id: Ifef9261959e31b2c1778a4cb0fd387d46ae01619
diff --git a/payload_generator/cow_size_estimator.cc b/payload_generator/cow_size_estimator.cc
index da4f896..bb12113 100644
--- a/payload_generator/cow_size_estimator.cc
+++ b/payload_generator/cow_size_estimator.cc
@@ -153,6 +153,9 @@
       .compression = std::move(compression),
       .max_blocks = (partition_size / block_size),
       .compression_factor = compression_factor};
+  // b/322279333 use 4096 as estimation until we have an updated estimation
+  // algorithm
+  options.compression_factor = block_size;
   auto cow_writer = CreateCowEstimator(cow_version, options);
   CHECK_NE(cow_writer, nullptr) << "Could not create cow estimator";
   CHECK(CowDryRun(source_fd,