message: Add shard count to tflite_convert_test target
  This is for removing flakiness of the test target.
diff: @@ -96,6 +96,8 @@ py_test(
  "@tflite_mobilenet_ssd_quant_protobuf//:tflite_graph.pb",
  ],
  python_version = "PY3",
  + # Increased thread count for reducing timeout failures.
  + shard_count = 4,
  srcs_version = "PY2AND3",
  tags = [
  "no_oss",
  