Remove flaky tests from the official plan

The following tests assumes a stable live-internet connection
with often a short round-trip time. Should be refactored to
test against a local server etc.

android.net.cts.SSLCertificateSocketFactoryTest#testCreateSocket
android.net.cts.SSLCertificateSocketFactoryTest#test_createSocket_bind
android.net.cts.SSLCertificateSocketFactoryTest#test_createSocket_simple
android.net.cts.SSLCertificateSocketFactoryTest#test_createSocket_wrapping
android.net.wifi.cts.NsdManagerTest

Bug: 18682315
Bug: 18680089
Change-Id: Icd716bb60ec0a1b8bcf0db3afae4b2f2e94f5973