Fix metered-constraint job scheduler CTS test

The test was incurring false positives in the case of the job running
even when the metered-network constraint didn't hold.  We now have a
test that verifies the negative: that the job fails to run, as expected,
when the device is connected via an unmetered network.

Along the way, we made setup/teardown of the wifi state more robust;
there was some flakiness arising from the previous handling.

Fix 62545908
Test: bit CtsJobSchedulerTestCases:.ConnectivityConstraintTest

Change-Id: I40269728aea5c7fef314d36a4b163dfa7d9eafa3
2 files changed