Sync too many retries

- When an one-shot sync with app-standby exempt fails too many times in a row,
drop the "exempt from app-standby" flag.

- Also obtain some constants from global settings so we can change them
in CTS.

Bug: 72443754
Test: Manual test (CTS WIP)

Change-Id: Ibdbb348a7ff26a0be04b8f2c256e1f6ead39907d