Rejuv proc fully restores stamina (#12533)

Co-authored-by: Werner <1331699+Arrow768@users.noreply.github.com>

code/modules/mob/living/living.dm

@@ -484,6 +484,7 @@ default behaviour is:
 	SetWeakened(0)
 
 	// shut down ongoing problems
+	stamina = max_stamina
 	total_radiation = 0
 	nutrition = 400
 	hydration = 400
@@ -1024,4 +1025,4 @@ default behaviour is:
 	return FALSE
 
 /mob/living/proc/is_anti_materiel_vulnerable()
-	return FALSE
+	return FALSE