This reverts commit f0153fa4c8.
This broke a whole set of FS-based volume drivers since it
didn't change the method signatures in those drivers to take
the new instance argument.
I was working on adding them but then just decided this
isn't even used right now so it's faster to revert.
When this is added back in, I want to see the
LibvirtBaseVolumeDriver class turned into an ABC and
the connect_volume and disconnect_volume methods turned
into abstractmethods in LibvirtBaseVolumeDriver so this
kind of thing does not happen again.
Change-Id: If1ee6d6e4004750f80424ec54d7dabc564ec9e06
Closes-Bug: #1675584