This patch extracts into its own independent test a test sub-block looking
for a race condition when not waiting on handlers to become idle:
there is no way to prevent the race from not happening when looking for
it this way. This makes the test flakky.
This new independent test is tagged with @FlakkyTest(tolerance = 3).
Test: ConnectivityServiceTest passes, with higher probability.
Bug: 31479480
(cherry picked from commit 6d278a5693)
Change-Id: I32632bb763585c23f1de5bb1811a384a35bf9f64
67e09ac87a