Introduce a new predefined CI variable CI_MERGE_REQUEST_DRAFT

Problem to solve

As a developer, I want specific CI jobs to be skipped when pushing commits to a merge request when it's a draft, to save time and iterate faster. In particular, I want long-running QA jobs to be skipped or to be manual.

As a customer running GitLab on-premises, I also want specific jobs to be skipped when a MR is a draft, to save resources.

Right now this can be achieved using predefined CI variable CI_MERGE_REQUEST_TITLE in CI rules, but these rules need to be complex to support the many ways a MR can be marked as a draft. Also, these rules are likely to get out of sync as the feature evolves. See documentation.

Proposal

Introduce a new predefined CI variable CI_MERGE_REQUEST_DRAFT that returns a boolean. true = mr is in draft.

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This page may contain information related to upcoming products, features and functionality. It is important to note that the information presented is for informational purposes only, so please do not rely on the information for purchasing or planning purposes. Just like with all projects, the items mentioned on the page are subject to change or delay, and the development, release, and timing of any products, features, or functionality remain at the sole discretion of GitLab Inc.