[tf.data] Increase the roll out percentage of optimization `enable_gradient_descent` to 5%.

PiperOrigin-RevId: 336717806
Change-Id: I724c31d9d2cb4cff1c867c168e52aa026c05c01f
diff --git a/tensorflow/core/kernels/data/optimize_dataset_op.cc b/tensorflow/core/kernels/data/optimize_dataset_op.cc
index 81fcf6d..6e079937 100644
--- a/tensorflow/core/kernels/data/optimize_dataset_op.cc
+++ b/tensorflow/core/kernels/data/optimize_dataset_op.cc
@@ -84,7 +84,7 @@
     // of the Borg jobs, the experiments will be randomly turned on.
     // clang-format off
     absl::flat_hash_map<string, uint64> live_experiments = {
-        {"enable_gradient_descent", 1}
+        {"enable_gradient_descent", 5}
     };
     // clang-format on
     auto hash_func = [](const string& str) { return Hash64(str); };