On slower test nodes we're seeing failures where the
2nd cinder volume created is not yet available by the
time we try to attach it to a server which fails with
a 400 InvalidVolume error. This fixes the bug by waiting
for the volume to be available before trying to attach it.
Change-Id: I833d79ecc97ddc844bf156ab64477c7c77424f20
Closes-Bug: #1807520
(cherry picked from commit 2f03ec23fd)
1a28c1e440