Look into removing tbVendor.VendorZoneId as a redundant column

Look into removing tbVendor.VendorZoneId as a redundant column. Either just remove the column as part of this story, or create a new story to remove it later and add to the backlog.

Places where we use VendorZoneId:

1) Load Testing Scripts (CorrectOnHand_EnsureVendorAndItemsExist.sql)
2) Rules Engine (MobileClientVendorItemRuleChange.vb) -> used to identify National Vendors from not national vendors
3) MMS Vendor page (MMS_HO_Distributors.aspx.vb) -> both a get and an update