CtsVerifier(wifi): Make the metered check more robust

Time taken to mark the network metered will vary dependening on what
traffic is ongoing, etc. Add a longer timeout & handle multiple
capabilities changed broadcast in that duration to ensure that the tests
are not flaky.

Bug: 140871464
Bug: 150236894
Bug: 150890482
Test: Manually ran all CtsVerifier tests.
Change-Id: I3930070103c340ca92b01c96269283fbafadb035
1 file changed