Tests: adjusted rate in limit_req_delay.t for slow hosts.

If the request for "rejected" test managed to be delayed far enough (~700ms+),
e.g. due to general slowness of the host, it could arrive too late for reject.

limit_req_delay.t

diff --git a/limit_req_delay.t b/limit_req_delay.t
index 21eb113..f8dea7b 100644
--- a/limit_req_delay.t
+++ b/limit_req_delay.t
@@ -36,7 +36,7 @@
 http {
     %%TEST_GLOBALS_HTTP%%
 
-    limit_req_zone $binary_remote_addr zone=one:1m rate=1r/s;
+    limit_req_zone $binary_remote_addr zone=one:1m rate=30r/m;
 
     server {
         listen       127.0.0.1:8080;