Create E2E test to generate an MR summary
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Test the `Summarize Code Changes` feature to ensure feature is working correctly from an end to end point of view. Test will need to be executed in a live environment to integrate with a AI provider.

Related feedback issue: https://gitlab.com/gitlab-org/gitlab/-/issues/443236
Related AI gateway inteway integration issue https://gitlab.com/gitlab-org/gitlab/-/issues/459868
TODO: need to confirm whether the current form of the feature will be the GA feature
Note: to enable feature in GDK, group needs to be ultimate:

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