iotests: Filter actual image size in 184 and 191

Whenever the actual image size is not part of the test, it should be
filtered as it depends on the host filesystem.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20171009163456.485-3-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
4 files changed