Fix the LV NotFound situation for thin-type LVM

If the logical volume is not found, LVM displays on the error output
that the volumes could not be found. So here, we filter on this very
specific situation, and let all the other cases go through the stack.

Added a test for this new code path, which raises an exception of the
proper type to be caught by the new code.

Change-Id: I703af8ccd87c6332d9f88eff63fcf26ebed234f4
Closes-Bug: #1390081