automation: reducing GWT workers
automation: reducing GWT workers

Reducing GWT workers to 1 in order to reduce memory
requirements for building.
(cherry picked from commit 6743d72023aed0d7a76e883b142e59bc856a9653)

Change-Id: I396a357b49194d70349870b62fd56f5f0b2f3b41
Signed-off-by: Sandro Bonazzola <fcb014d63786651910af5db2ecc5316c668188ef@redhat.com>

eayun/ovirt-engine,zerodengxinchao/ovirt-engine,yingyun001/ovirt-engine,walteryang47/ovirt-engine,zerodengxinchao/ovirt-engine,zerodengxinchao/ovirt-engine,yapengsong/ovirt-engine,walteryang47/ovirt-engine,yapengsong/ovirt-engine,eayun/ovirt-engine,yingyun001/ovirt-engine,walteryang47/ovirt-engine,yingyun001/ovirt-engine,yapengsong/ovirt-engine,walteryang47/ovirt-engine,eayun/ovirt-engine,zerodengxinchao/ovirt-engine,yapengsong/ovirt-engine,yingyun001/ovirt-engine,eayun/ovirt-engine,zerodengxinchao/ovirt-engine,yingyun001/ovirt-engine,walteryang47/ovirt-engine,eayun/ovirt-engine,yapengsong/ovirt-engine