@Ignore ConnectivityServiceTest#testRequestBenchmark

Ignore the last remaining test in ConnectivityServiceTest with spurious
failures. testRequestBenchmark has some intrinsic chances of failure due
to the fact it attempts to assert elapsed time durations against a
reference target.

Bug: 32561414
Test: no functional change
Change-Id: Ib25d76581b47997b2ef84df3e6a9fd9224b85d92