Make ENABLE_ROLLBACK_TIMEOUT configurable

Bug: 112431924
Test: atest RollbackTest
Test: manual testing
      - disable the RollbackManagerService by commenting out
        BroadcastReceiver for ACTION_PACKAGE_ENABLE_ROLLBACK
      - configure timeout: adb shell device_config put rollback
        enable_rollback_timeout 60000
      - install apk: adb install --enable-rollback
        out/target/product/taimen/data/app/RollbackTest/
        RollbackTest.apk
      - search for "rollback timed out" in `adb logcat`

Change-Id: I61600cf376755d80c735ad954a80ca98de508bda