This reverts commit a55bbbfa19.
The series of patches involved with adding this feature introduced
an unexpected dependency on glance's v2 API, which we do not
currently support. Triggering a user-facing bug quickly, and leaving
some uncertainty about what else is likely to come in the future,
a revert of this code was decided given the short time to -rc1.
Closes-bug: 1291014
Change-Id: I2ed6a861e583b9513b0984ff9801d4b9f7536798