Tests: cope with resolver resend in mail resolver tests.

Currently, if resolver didn't find PTR type in the answer section of PTR
response, it keeps the node in the resend queue until the next timer event.
diff --git a/mail_resolver.t b/mail_resolver.t
index 8a80d37..e4227cf 100644
--- a/mail_resolver.t
+++ b/mail_resolver.t
@@ -62,7 +62,6 @@
         protocol  smtp;
         resolver  127.0.0.1:%%PORT_8083_UDP%%;
         resolver_timeout 1s;
-
     }
 
     server {
@@ -81,6 +80,7 @@
         listen    127.0.0.1:8031;
         protocol  smtp;
         resolver  127.0.0.1:%%PORT_8086_UDP%%;
+        resolver_timeout 1s;
     }
 
     server {