Remove unused branches in UUI

The jobs especially the docker build jobs running on Istanbul branch
will override the UUI docker images with tag latest.

UUI doesn't need running on Istanbul branch anymore, so remove it.
And there is no Kohn branch yet, also remove it.

Signed-off-by: xudan16 <xudan16@huawei.com>
Issue-ID: CIMAN-420
Change-Id: Iec5dbc6fc357e84faf892075e17964b481ce67b8
4 files changed