Enable daily scheduled pipeline by default

Problem to solve

Security Reports and dashboards are only updated when pipelines are run. For projects with low activity, it means that vulnerabilities will be detected only once a new pipeline is triggered, generally when a commit is pushed.

Further details

Follow up of https://gitlab.com/gitlab-org/gitlab-ee/issues/6941#note_98934622, I'd like to challenge the idea of having a default scheduled pipeline running daily. It's useful from a security perspective, but also helps to ensure a project can still be built and tested at all times. Issues with dependencies (like yanked gems) are also easier to debug and fix when detected as soon as they occur.

Proposal

Allow users to set a scheduled pipeline.

What does success look like, and how can we measure that?

A pipeline runs every day for the main branch.

Links / references

Edited by Nicole Schwartz