after DNS Query flooding during DNS timeout test.
DNS timeout test requires flooding device with DNS queries.
This causes problem to ESP8266 module causing it to stuck for 11 sec.
In result all following tests fails. To avoid this "smart delay" is added.
If device preforms gethostbyname correctly then tests can proceed.
Otherwise after 1 sec sleep gethostbyname is repeated until success or re-check limit (set to 15).
Thanks to this all ethernet and non ESP8266 wireless devices don't need to wait but ESP must wait.
The test floods the device with UDP requests (it skips the 100 ms delay to simulate instant timeout). ESP8266 starts responding with "busy p..." message. It needs more time to process the data and recover for subsequent tests.