Missing dependency should fail job

Currently, our dependencies are "soft", we do not fail the job if the dependency is missing, which is wrong.

Missing dependency should not allow the subsequent stage to be executed and should fail the job.

• A depending job has dependencies keyword, but a depended job can not be found. (This is described at https://gitlab.com/gitlab-org/gitlab-ce/issues/18769)

• A depending job has dependencies keyword and a depended job can be found, but the depended job’s artifacts are missing by some reasons(e.g. expired or deleted manually, or job is manual and not executed)

cc @grzesiek @bikebilly