Do not create pipelines with only .pre/.post jobs
Summary
Pipelines that have jobs only from the .pre/.post
stages should be considered empty and not persisted.
Steps to reproduce
pre-checks:
stage: .pre
script:
- echo "running a job from .pre stage"
post-checks:
stage: .post
script:
- echo "running a job from .post stage"
This config should not trigger any pipelines