Plug in DeviceConfig to Variables in Flexibility Controller

Added the ability to adjust the percents that the number of constraints
get dropped, fallback flexibility deadline, minimum time between alarms,
hard cut off for flexible constraints, and if flexible constraints
should be applied at all.

Bug: 239925946

Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/job
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/job
Test: atest CtsJobSchedulerTestCases
Change-Id: I8b8c1dcf74f74f2ad171d2fc1c51a3571f5e8a8a