lava_create_jobs.py: Reinstate build URL metadata

Fix regression from ac2d0f0771a where generation of metadata item for LAVA
job definitions was removed.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Ie19af7fc5122651823105e95b3cc04a555148caa
1 file changed