Enable FF ci_variable_for_group_gitlab_deploy_token

What does this MR do and why?

This MR enables the feature flag ci_variable_for_group_gitlab_deploy_token.

It's already been enabled on GitLab.com since 2022/06/15.

• Bug issue: #214014 (closed)
• Introduced in: !88696 (merged)
• Rollout issue: #363621 (closed)

MR acceptance checklist

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