tests: proper ubifs size tests
tests: proper ubifs size tests

ubifs does not store 'empty' space in the image, hence the image may be
significantly smaller than desired rootfs size (MENDER_CALC_ROOTFS_SIZE). Assume
that it will be no less than 30% of partition size.

Changelog: none

Signed-off-by: Maciej Borzecki <f609d9f713abcd5f8f0e51f08dc151638a7681e7@rndity.com>

bboozzoo/meta-mender,bboozzoo/meta-mender,bboozzoo/meta-mender,bboozzoo/meta-mender