Force serial I/O for EnKF on Hera

There is an issue with parallel netcdf specifically for ensemble runs
on Hera, so code to force serial output there is restored to the EnKF
config.

Refs: NOAA-EMC#600

parm/config/config.efcs

@@ -18,6 +18,12 @@ if [ $QUILTING = ".true." ]; then
     export npe_efcs=$npe_fv3
 fi
 
+# Only use serial I/O for ensemble on Hera
+if [[ "$machine" == "HERA" ]]; then
+    export OUTPUT_FILETYPE_ATM="netcdf"
+    export OUTPUT_FILETYPE_SFC="netcdf"
+fi
+
 # Number of enkf members per fcst job
 export NMEM_EFCSGRP=2
 export RERUN_EFCSGRP="NO"