Remove ALIASES block from template util

These alias warnings were removed in #38218 for 2017.7.

salt/utils/templates.py

@@ -73,10 +73,6 @@ class AliasedLoader(object):
         return getattr(self.wrapped, name)
 
     def __contains__(self, name):
-        if name in ALIASES:
-            salt.utils.warn_until('Nitrogen', ALIAS_WARN)
-            return ALIASES[name] in self.wrapped
-        else:
         return name in self.wrapped