Resolve "Display mlflow run uuid on Candidate page"

What does this MR do and why?

Due to changes on how we were handling Candidate iid, mlflow uuids are not being displayed anymore. This adds a fields to Candidate details page showing the property

Screenshots or screen recordings

Before	after

How to set up and validate locally

1. Enable the feature flag

   echo "Feature.enable(:ml_experiment_tracking)" | bundle exec rails c

2. Create an experiment and a candidate

   user_id = 1 # if you are using root
   project_id = 1 # not necessarily 1, but the project you are using for testing. On a pristine gdk installation, project 1 is usually `toolbox/gitlab-smoke-tests`
   exp = Ml::Experiment.create!(name: 'Gitlab Experiment', user_id: user_id, project_id: project_id)
   c = exp.candidates.create!(user_id: user_id, start_time: 0, internal_id: 1, project_id: project_id)

3. Navigate to the candidate "/path_to_project/-/ml/candidates/1".

4. Check that MlFlow un UUID is now added

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #408845 (closed)