style: use variable instead of hardcoded

etc/slurm/job_submit.lua

@@ -26,6 +26,9 @@ local grp = require("posix").grp
 function slurm_job_submit(job_desc, part_list, submit_uid)
 
    local target_group = "gpfs5"
+   local target_feature = "gpfs5"
+   local default_feature = "gpfs4"
+
    local username = pwd.getpwuid(submit_uid).pw_name
    local group_member = grp.getgrnam(target_group).gr_mem
    local found = false
@@ -35,12 +38,12 @@ function slurm_job_submit(job_desc, part_list, submit_uid)
    for i,member in ipairs(group_member) do
       if member == username then
          found = true
-         job_desc.features = "gpfs5"
+         job_desc.features = target_feature
          break
       end
    end
    if not found then
-      job_desc.features = "gpfs4"
+      job_desc.features = default_feature
    end
 
    slurm.log_info("username:" .. username)