Investigate why Filter mechanism does not work for XSRF filtering from HS2

While working on HIVE-13853, it was found that simply using the constructed Filter as-is from ThriftHttpCLIService was not working, and thus, needed explicit calling of the filtering method from ThriftHttpServlet was needed.

We should investigate why that other method did not work, and make it fall inline with filter usage, so as to not need to call functions inside the filter. Also, this is a prerequisite for eventually getting rid of our shim if we later update to always expecting hadoop versions that contain the filter