Update UI execution limits.

Set the minimum UI execution guarantee to 6 hours and the maximum
execution limit to 12 hours. Put the data estimate calculation based
limits behind a flag that is off by default.

Bug: 261999509
Test: atest FrameworksMockingServicesTests:JobSchedulerServiceTest
Change-Id: Id3ef5b64a4ca3ff53088318c969f22ca995f6faa