Update primary obsproc JJOB call in prep.sh

The updated obsproc package renamed the primary global JJOB script
and the HOMEobsproc variable is the only home path for the package,
so update prep.sh to now call:
$HOMEobsproc/jobs/JOBSPROC_GLOBAL_PREP
instead of the old:
$HOMEobsproc_network/jobs/JGLOBAL_PREP

Refs NOAA-EMC#1033

jobs/rocoto/prep.sh

@@ -109,7 +109,7 @@ if [ $DO_MAKEPREPBUFR = "YES" ]; then
         export MAKE_NSSTBUFR="NO"
     fi
 
-    $HOMEobsproc_network/jobs/JGLOBAL_PREP
+    $HOMEobsproc/jobs/JOBSPROC_GLOBAL_PREP
     status=$?
     [[ $status -ne 0 ]] && exit $status