Differentiate between jobs run with Enforce template inclusion in pipelines

Problem

https://gitlab.com/gitlab-org/gitlab-ee/issues/8429 introduces enforcing template inclusion in pipelines, it is however not currently possible to differentiate between jobs run from your own pipeline configuration and those from the instance default.

Further information

Coming from https://gitlab.com/gitlab-org/gitlab-ee/issues/8429#note_178144833

Proposal

Add a tag on the jobs which makes this clear.