Remove leftover migration helpers.

https://reviews.apache.org/r/12673/


git-svn-id: https://svn.apache.org/repos/asf/incubator/wave/trunk@1505140 13f79535-47bb-0310-9956-ffa450edef68
Remove migration test case following 1505140

(I may have forgotten about these, until the build error'd)
Part of https://reviews.apache.org/r/12673/


git-svn-id: https://svn.apache.org/repos/asf/incubator/wave/trunk@1511113 13f79535-47bb-0310-9956-ffa450edef68