Reduce test flakiness.

Ask JobScheduler to run jobs when we want them to run, but only if the
constraints are satisfied. Also increased wait times slightly.

Bug: 138253466
Test: atest --iterations 10 android.jobscheduler.cts.JobThrottlingTest
Change-Id: Ia0bcf00b26a4521a4cfe89b2f5f5edcfb111ccf6