Fix the quota exempted window size tuning issue through device config

Bug: 412323410
Test: atest FrameworksMockingServicesTests:com.android.server.job.controllers.QuotaControllerTest
Test: Run adb shell device_config put jobscheduler qc_window_size_exempted_ms XXX
      and verify the output
Flag: EXEMPT bugfix
Change-Id: Ie5665becdeaa9f2cc694f45ae90c9ae75dbf6658