Fix ConnectivityController running job counting.

Use a Set of running jobs so that ConnectivityController has a clear
understanding of how many jobs are running. In the process, also fix the
issue where controllers would think that a job was running even though
it had actually failed to start.

Bug: 184740668
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/job
Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/job
Test: atest CtsJobSchedulerTestCases
Change-Id: Iff142e63b2a3cb92c9467608f95401c7a0f287ee