Add Application Setting for Live Job Trace

What does this MR do and why?

This MR converts and existing feature flag :ci_enable_live_trace into an application setting :ci_job_live_trace_enabled.

• Existing feature flag is default set to false but the feature is being used and some self managed instances have the feature enabled
• for this reason, this MR will be done in 2 steps:
  • add the new setting that still defaults to the feature flag if it is enabled but also allows users to set the setting. Backfill setting with existing Feature flag value. Since docs with updated enablement instructions added, the feature flag is no longer used.
  • raise a second MR that fully removes the feature flag now that setting is backfilled
• feature requires object storage to be configured and though we did allow users to enable the feature flag without enabling object storage, the setting implementation adds a conditional that validates whether object storage is configured when setting is true

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. run your gdk locally
2. log in as a user with admin role (the root user will work)
3. Navigate to CI/CD settings --> http://gdk.test:3000/admin/application_settings/ci_cd
4. Observe the new setting drop down at the bottom

Note: You will not be able to enable the setting without error unless you have local storage enabed, I am unsure how to do that locally, but the tests do cover this scenario

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Related to #350883 (closed)