Introduce feature flag for owner filtering of runners

What does this MR do and why?

Introduce feature flag for owner filtering of runners

Add the feature flag which will allow the Group and Project tokens to be made visible and be used.

This merge request also alters the order of the tokens in the drop down menu.

This is merge request 3 of 3

References

• Merge Request with all changes: Filter runners by Group and Project on Admin da... (!180396 - closed)
• Merge Request 1 of 3: Filter runners on admin page by owning Group (!209513 - merged)
• Merge Request 2 of 3: Filter runners on admin page by owning project (!218500 - merged)
• Epic: &7164 (closed)
• Issue: #378558
• Backend MR (merged): !150347 (merged)

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Visit the admin/runners page to see the absence of Project and Group selections

2. In rails console, enable the feature flag

   Feature.enable(:filter_runners_by_project_and_group)

3. Refresh the page to have the Project and Group tokens appear

4. Select either one to highlight that they cannot be used in the same query

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