IOT-1807: Disabling discovery tests to improve productivity of other developers.

IOT-1807: Disabling discovery tests to improve productivity of other developers.

More details:
1. Tests don't check if the timeout has been hit, so they do not
   report failures properly. By looking at Jenkins it's clear, that
   the timeout issue is happening in most cases.
2. The tests fail randomly from time to time, if the test's callback
   is called, so the timeout is NOT hit and the tests are actually
   doing their job, indicating that something works incorrectly.

This change is ment to prevent other developers from being
disturbed by the random test failures, which should be eventually
fixed in IOT-1807.

Change-Id: Ibe25cd2adc74ec0676719a1ec506977c35ec20ce
Signed-off-by: Pawel Winogrodzki <pawelwi@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/17327
Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: Dan Mihai <Daniel.Mihai@microsoft.com>