Adds consent step to workflow for providing a trial subscription

Why is this change being made?

L&R Support often provides trial licenses to customers to keep their instance running while the renewal process completes. Trials, however, exclude some GitLab features on which a customer may rely for daily operations. Right now, we have no documented or consistent process for verifying with a customer whether they use any of those features or whether the absence of them will be a problem. As a result, we get some urgent tickets from upset customers who were unaware of what would happen when they applied the trial license.

Author Checklist

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
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• If the changes affect team members, or warrant an announcement in another way, please consider posting an update in #whats-happening-at-gitlab linking to this MR
  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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