test_integration.erb - fix intermittent test (#1924)

Fixes test_sigterm_closes_listeners_on_forked_servers

When the test was added in PR #1802, it used the rackup/1second.ru file, which provided a fixed one second delay.

PR #1903 removed the 1second.ru file and added a sleep.ru file, which allowed variable timing.  But, the 'sleep1' path was added to only one of the test's two connect calls.

The test has passed most of the time, but intermittently fails.  This adds the 1 second delay to the 2nd connect call, which should make it stable.

test/test_integration.rb

@@ -267,7 +267,7 @@ def test_sigterm_closes_listeners_on_forked_servers
         mutex.synchronize { condition_variable.wait(mutex, 1.5) }
 
         begin
-          s = connect
+          s = connect "sleep1"
           read_body(s)
           next_replies << :success
         rescue Errno::ECONNRESET