JobScheduler: Fix some test failures

Mock the JobSchedulerInteral object when the tests need to create
HIGH priority JobStatus objects.

Bug: 437782438
Test: atest FrameworksServicesTests:com.android.server.job
      atest FrameworksMockingServicesTests:com.android.server.job
Flag: EXEMPT test fix
Change-Id: Ibf87e9aaf3a049c10f4cd644a2dcc7e689362935