gerrit-sync-ve: move hook init just before push

Change-Id: Ib795870c3be1b07d59d7cfdecf2cf8a187475c74
gerrit-sync-ve: clone anon repo, push over ssh

Change-Id: I7c944947e23305296ab70396175ff3f47935f3aa
gerrit-sync-ve: split update and pushing

The update of the VE repository is done by 'jenkins-slave' user but the
push to Gerrit and approval has to be made by 'jenkins' user which has
the SSH credentials for the Gerrit 'jenkins-bot' user.

gerrit-sync-ve-push.sh basically push and approve --submit.

Change-Id: I899986910bf207c034107c7992aaa5fad4336a39