user-util: switch order of checks in valid_user_group_name_or_id_full()

When we are supposed to accept numeric UIDs formatted as string, then
let's check that first, before passing things on to
valid_user_group_name_full(), since that might log about, and not the
other way round.

See: #15201
Follow-up for: 93c23c9297

src/basic/user-util.c

@@ -778,10 +778,10 @@ bool valid_user_group_name_or_id_full(const char *u, bool strict) {
         if (isempty(u))
                 return false;
 
-        if (valid_user_group_name_full(u, strict))
+        if (parse_uid(u, NULL) >= 0)
                 return true;
 
-        return parse_uid(u, NULL) >= 0;
+        return valid_user_group_name_full(u, strict);
 }
 
 bool valid_gecos(const char *d) {