Fix Request Access User

What does this MR do and why?

Fix Request Access User

We need to use a user that we can add to the private project where access requests are captured. The automation-bots aren't invitable users. This is causing the "Operation not allowed" error.

How to set up and validate locally

1. In rails console enable the feature flag for a group

   Feature.enable(:observability_sass_features, Group.find_by_path('flightjs'))

2. Also in console, create a gitlab bot user:

   User.create!(username: "gitlab-bot", email: "bot@gitlab.com", namespace: User.first.namespace, password: "GobbleGook", name: "Gitlab  Bot")

3. Visit the request access page for the group: http://localhost:3000/groups/flightjs/-/observability/access_requests/new
4. Click the Enable Observability button
5. The page should say "Access Request Submitted"
6. There should be a confidential request access issue in the first project for the group http://localhost:3000/groups/flightjs/-/issues with the title "Request Observability Access for Flightjs"