Tables and columns to be skipped for monitoring updates are not configurable

Today we skip some tables fully and selective columns of other tables in Open_vSwitch and HWVTEP plugins as part of fixes for bugs 6463, 7201 etc. However there is no way to let user configure which tables and columns to skip. Some use cases require statistics or status information. Also, when doing scale/perf testing it becomes difficult to skip any extra columns or allow few extra tables/columns without access to code.