Metrics: Delete UI code for health tab in cluster view

⚠ Removal should take place in %16.0 or later.

As part of #346541 (closed) remove Health tab from Infrastructure > Cluster

Relevant files

frontend cluster health

• app/assets/javascripts/pages/projects/clusters/show/cluster_health.js
• app/assets/javascripts/pages/projects/clusters/show/index.js
• app/views/clusters/clusters/_health.html.haml
• app/views/clusters/clusters/_health_tab.html.haml

frontend integrations

• app/views/clusters/clusters/_integrations.html.haml
• app/views/clusters/clusters/_integrations_tab.html.haml
• app/assets/javascripts/clusters/forms/show/index.js relates to the base cluster setup
• app/assets/javascripts/clusters/forms/components/integration_form.vue relates to the base cluster setup
• app/assets/javascripts/clusters/forms/stores/index.js relates to the base cluster setup
• app/assets/javascripts/clusters/forms/stores/state.js relates to the base cluster setup

documentation

• doc/user/clusters/integrations.md already removed
• doc/user/infrastructure/clusters/manage/clusters_health.md already removed

Implementation plan

1. delete Health tab on Infrastructure > Cluster
2. delete relevant docs

Verification steps

These areas of the app should remain unavailable & without regressions to other features: