Add script and job to push the 4 Horizon translation source files
(4 English po files) to Transifex.
Since Horizon has two "locale" folders in different position,
it's not able to levarage the existing upstream_translation.sh
and have to add a new upstream_translation_horizon.sh.
Change-Id: I7a42365414a6a5dcde276bc10761b08e3e756931
e5674d0635