Hard-coded uuids for drug order type and test order type

OpenMRS has hard-coded uuids in the API service to look up the order type for "Drug Order" and the order type for "Test Order". 

However, there is no requirement or enforcement in the system that OpenMRS implementations have Order Types with these uuids, and in fact the system explicitly supports the ability to have multiple order types to represent drug orders and test orders via the "javaClassName" property.

Any place in the codebase where these constants are looked up should be evaluated to determine if looking up by javaClassName is the better and more correct approach, and we should do everything we can to remove any dependencies on these specific uuids.