ensemble runs append string _ensNN twice to icebergs restart files causing them not to be read

[nikizadehgfdl]

Restart tests for ensemble runs fail because the icebergs restart file names from each ensemble member has the ensemble_id appended twice like
icebergs.res.ens_01.ens_01.nc instead of
icebergs.res.ens_01.nc
and so they are ignored when the model restarts.