Add ready checks for the microserver and ATS test instances. (#6625)

This fixed failing autest runs for nghttp on 8.1.x, adding to master first

(cherry picked from commit 21f6a70)

Author: ezelkow1

tests/gold_tests/h2/nghttp.test.py

@@ -80,7 +80,7 @@
 tr.Processes.Default.Command = "nghttp -v --no-dep 'https://127.0.0.1:{0}/post' --trailer 'foo: bar' -d 'post_body'".format(
     ts.Variables.ssl_port)
 tr.Processes.Default.ReturnCode = 0
-tr.Processes.Default.StartBefore(microserver)
-tr.Processes.Default.StartBefore(Test.Processes.ts)
+tr.Processes.Default.StartBefore(microserver, ready=When.PortOpen(microserver.Variables.Port))
+tr.Processes.Default.StartBefore(Test.Processes.ts, ready=When.PortOpen(ts.Variables.ssl_port))
 tr.Processes.Default.Streams.stdout = "gold/nghttp_0_stdout.gold"
 tr.StillRunningAfter = microserver