Improve AllowedPullPolicies error message
This is a follow-up from gitlab#21619 (closed) and #26753 (closed).
MRs: gitlab!85588 (merged), !3422 (merged), !3412 (merged)
When an unallowed pull policy is defined, we show this error:
However, we don't specify where this pull policy is defined. In the CI config YAML file or the Runner config.toml
file?