Use version dir, not LATEST for Percona d/l path

The Percona download URL is pinned to a specific verson but LATEST is in
the path. This means new Percona releases cause 404's until we update the
version.

Also updating the version for good measure.

Change-Id: Ib21666b01f7ef9fd72eb0f868e8eb76d6832fe9e
Merge "Use version dir, not LATEST for Percona d/l path"