This test currently only works with AmarisoftENB and srsUE, because:
* srsENB has no handover support yet
* AmarisoftUE doesn't provide any known way to verify handovers.
As a result, it usually runs with following filters and modifiers:
amarisoftenb-rftype@uhd+srsue-rftype@uhd+mod-enb-ncells@2+mod-enb-meas-enable
The get_counter() API may change in the future based on information
available from other implementations.
Change-Id: I0dff4af7e3a89804a03842ad4a4d697bca3a9773
