The volume v2 functional tests occasionally fail with
"unrecognized arguments: --private". This appears to occur when
volume v1 and volume v2 functional tests are run at the same time
when one or more of the tests do not set OS_VOLUME_API_VERSION
appropriately.
This patch also fixes a timing issue seen when running the
tests locally due to a missing wait and moves the snapshot
test to volume v2 since it was written for v2.
Change-Id: I9c9863fe1aef81b0564920f36452c6f27211d5ba
Closes-Bug: #1589793
09b783ad3e