[develop] Revert back to old way of setting FIXdir (#670)

The way the fix directory is set changed in PR #609, specifically item number 3.
I think this has been causing an issue with forced run_envir=nco mode. I don't have a full explanation for this at the moment, but reverting back to old way of setting FIXdir seems to atleast partially fix the issue. I was able to run fundamental tests successfully on Hera using run_envir=nco.

ush/config_defaults.yaml

@@ -676,7 +676,7 @@ workflow:
   #
   #-----------------------------------------------------------------------
   #
-  FIXdir: '{{ EXPTDIR if user.RUN_ENVIR == "community" else [user.HOMEdir, "fix"]|path_join }}'
+  FIXdir: '{{ EXPTDIR if workflow_switches.RUN_TASK_MAKE_GRID else [user.HOMEdir, "fix"]|path_join }}'
   FIXam: '{{ [FIXdir, "fix_am"]|path_join }}'
   FIXclim: '{{ [FIXdir, "fix_clim"]|path_join }}'
   FIXlam: '{{ [FIXdir, "fix_lam"]|path_join }}'