Modify app scheduling module thread.

Shift the dedicated thread to default priority
and rename it to reflect what it covers.

Bug: 268097442
Test: atest AppStandbyControllerTests
Test: atest CtsAlarmManagerTestCases
Test: atest CtsJobSchedulerTestCases
Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/alarm
Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/job
Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/tare
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/job
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/tare
Change-Id: Id69dd108c332329da16c0228aa473965b253b2b8