Parameterize the iperf3 bidirectional test for the 4g test suite to execute a
given number of UEs. By default, the number of ue is 1.
Change-Id: I34fb436d581eda12388819b5dee9a3bafd419a7f
this allows, without changing the test case, to use a custom
template, which is useful for development. By default, nothing changes
and the OGT template is used
Change-Id: Ifc43ac41b16813116f2559da5223a6fecc186125