Adjust callbacks on handler thread.

Move most instances to adjusting per-UID network callbacks to the
handler thread to reduce scheduling & cancelling latency.

Bug: 141645789
Test: atest CtsJobSchedulerTestCases:ConnectivityConstraintTest
Test: atest CtsJobSchedulerTestCases:JobThrottlingTest
Test: atest FrameworksMockingServicesTests:ConnectivityControllerTest
Change-Id: I9aa448310bd972db76406376e46cae37516ae526