The 1.2m drop test is not part of the UN Test 38.3. The 1.2m test is mandatory for a battery only shipment (PI 965 and PI 968) and for a battery packed with equipment shipment (PI 966 and PI 969). The shipper is required to perform the test and check the result.
All shipments are based on mutual trust. There is no test certificate. If in doubt, the carrier may ask for a statement or even refuse the shipment if the carrier cannot trust the shipper.
The 1.2m drop test is not required for shipments where the battery is already installed in the equipment (PI 967 and PI 970). This is because the battery will then be protected by the equipment and by the outer packaging, and even if the package is dropped there is remote chance of breakage and resultant fire.