Remove suffixes from LVM brick test vgs output

When fake_execute() is called to retrieve volume group information, the
--nosuffix flag is passed but ignored.  This patch honors the nosuffix
flag and removes the unit suffix from the volume group sizes in the
returned output.

Change-Id: I45f41bc58f4ffb4bd527336c0f760350cff7c355
(cherry picked from commit a3ebe1fbaf90b0419a90c7b7dd6f76f59c676752)
Merge "Remove suffixes from LVM brick test vgs output" into stable/havana