Fix ZenModeRepositoryTest flag flipping

Turns out we need to have the SetFlagsRule in the class (normally I
didn't worry about it because it was in SysuiTestCase).

Fix: 352289773
Flag: TEST_ONLY
Test: this
Change-Id: I09773a6c95f97df28515b84f050f1c6370b5c37e
1 file changed