test: flag one more notmuch new test as broken

Drop the test update added in [1] and mark the test as broken, like the
tests flagged as broken in [2]. These all reflect the same underlying
breakage with (lack of) directory deletion.

[1] commit e4e04bbc328f990e36b77f508aef904d156029b1
[2] commit ed9ceda623d3f22fb66365b33db63c5c982067d3