roles/postfwd: Disable the email limits for the aur

Since the AUR is high email traffic, apply the same rule as for luna,
and add the sasl_username for aur to the no limits list.

roles/postfwd/templates/postfwd.cf.j2

@@ -13,6 +13,7 @@
 # luna is handling mailman and other services that distribute a lot of mail.
 &&NO_RATE_LIMIT_USERS {
         sasl_username=luna
+        sasl_username=aur;
 };
 id=NoRateLimit;
         protocol_state==END-OF-MESSAGE;