Mark Spdy3ConnectionTest#serverSendsSettingsToClient as known failure.

This test is flaky both on Android Pie and the latest development branch.
I haven't looked too deeply into _why_ it is failing, so it _could_
indicate a serious problem, but since the test on the surface is testing
functionality that isn't used on Android, it might not be worth
investigating. This CL marks the test as a known failure.

Bug: 116289659
Bug: 138134183
Test: Treehugger

Change-Id: I42eecda4fdf6483d55702a717c7c1f35e8699df7
1 file changed