Explicitly set CI policies

Usually, we want attributes merge_when_pipeline_succeeds and remove_source_branch enabled for MRs.

The script apertis-pkg-merge-upates-downstream does the right thing. But, our other job scan-licenses runs a scan and typically adds a new commit. On push of that commit, the above attributes are not specificed and thus the previous attributes, if any, seem to be dropped.

Signed-off-by: Ritesh Raj Sarraf ritesh.sarraf@collabora.com