Reduce gdas builds to 8 NOAA-EMC#2029 (NOAA-EMC#2036)

Reduce the default number of build jobs for the GDASApp to 8 from 16.

This is needed for Orion as the build crashes during a linking step.  Though not verified, it
appears this may be caused by using too much memory with 16 builds.  The issue disappears
when using 8 build jobs.

Resolves NOAA-EMC#2029

sorc/build_all.sh

@@ -141,7 +141,7 @@ fi
 
 # Optional DA builds
 if [[ -d gdas.cd ]]; then
-   build_jobs["gdas"]=16
+   build_jobs["gdas"]=8
    big_jobs=$((big_jobs+1))
    build_opts["gdas"]="${_verbose_opt}"
 fi