core macros – overlay of NO_UPKEEP macro

The past change in 1.15 changed not only internal things,
but also the overlay given by the NO_UPKEEP macro.

Now it gives the same overlay as the loyal trait does.
Which is also the same which this macro gave in 1.14.

data/core/macros/unit-utils.cfg

@@ -176,7 +176,11 @@
     # Use this when you don't want to use up a traits slot.
     [+unit]
         [+modifications]
-            {TRAIT_LOYAL_HERO_NOSLOT}
+            {TRAIT_LOYAL}
+            [+trait]
+                male_name=""
+                female_name=""
+            [/trait]
         [/modifications]
     [/unit]
 #enddef