Migrate to updated Kudu insert string API

In Kudu 0.10 the Insert API changed for Strings and Binary values to avoid ambiguity around memory copying. They changed SetString() to copy the value given to it to avoid misuse, and added a SetStringNoCopy() with the old behavior. We should use the new call.

Kudu commit:
https://github.com/apache/kudu/commit/48766a4ce17d422ced9a6ec78c9a9969ac44d8c9