Improve DORA performers score panel error states

What does this MR do and why?

Use the shared error state from the PanelBase, instead of rendering a custom GlAlert. Doing so gives a more consistent experience with the rest of the shared analytics dashboard panels, as well as enables the user to retry failed renders

I also renamed DoraPerformersScore to DoraPerformersScoreChart to avoid the name overlap with the parent component, which was causing some confusion

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

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Before	After

How to set up and validate locally

1. Please make sure that you have a GitLab Ultimate license
2. Seed a new group & project: SEED_DORA=1 FILTER=dora_metrics bundle exec rake db:seed_fu
3. Feature.enable(:dora_performers_score_panel, Group.find(<group-id>))
4. Feature.enable(:group_analytics_dashboard_dynamic_vsd, Group.find(<group-id>))
5. Seed DoraPerformanceScoreCounts data for your project
6. Visit the Value streams dashboard for your chosen group (http://{YOUR_INSTANCE}/groups/{GROUP_PATH}/-/analytics/dashboards/value_streams_dashboard)
7. To mock the error states, you can comment out this line, and reverse the condition on this line

Related to #421986 (closed)