Fix ZenModeRepositoryTest failures

One issue was that the arg captor wasn't accounting for the extra params
we added in ag/28185825. The second issue was that @DisableFlags wasn't
working correctly, so we need to use lazy initialization (b/352296216).

Bug: 352289773
Test: ZenModeRepositoryTest
Flag: EXEMPT trivial change + test-only change
Change-Id: Ibfcf370aea71c94bcacac7399f68f065c7ca6a03
2 files changed