[Apps] GitLab Manager - blueprint (DataDog#21028)

* [Datadog Workflows] create/update file

* Update gitlab-manager.json

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Co-authored-by: datadog-datadog-prod-us1[bot] <88084959+datadog-datadog-prod-us1[bot]@users.noreply.github.com>
Co-authored-by: Ameesha Isaac <ameesha.isaac@datadoghq.com>

Author: 3 people