Updated xfail reason for calendar fail

Changed wait to one that makes more sense

The bug that this test was xfailed against was marked as a duplicate, and the bug that it duplicated was marked fixed, so I'm not sure that the actual bug was getting any attention.

I have opened https://bugzilla.mozilla.org/show_bug.cgi?id=862167 for it and updated the manifest. I also changed a wait during my testing to one that makes more sense (to me anyway).