Temporarily ignore testAddAutomaticZenRule_claimedSystemOwner.

For some reason this test is taking 10 seconds to run, and ignoring it for now might nudge the notification tests module back below the timeout threshold until we have a better longer-term solution.

Bug: 398023814
Bug: 399685959
Test: this
Flag: EXEMPT test fix
Change-Id: Ia7d072b108a2098cd11333d46cf0125d5acc7e3f