CI: Specify project id and masterbranch manifest, add variable for the ci rev

* The master branch manifest needs to be specified here, as the kirkstone branch
includes the same files and needs to use kirkstone as master branch
manifest
* The project id needs to be specified here, as the 'manifest.yml' will
be included in multiple manifest repos with different ids.
* Putting the gitlab-ci-rev into a variable allows it to use it in
further ci steps. The 'deploy-gitlab-cy' step of the gitlab-ci repo
should update this value as well, as a plain substitution of the hash is
used.