Logging: Delete UI code for viewing pod logs

Why are we doing this work

In %15.0, we disabled/removed pod logs by moving it behind a feature flag.

⚠ Removal should take place in %15.2 or later.

Tracking issue for all logging removal work: Monitor:Logging Deprecation (#346485 - closed)

Relevant links

frontend files:

• app/assets/javascripts/logs/*
• app/assets/javascripts/environments/components/deploy_board.vue
• app/assets/javascripts/environments/components/environments_table.vue
• app/assets/javascripts/monitoring/components/dashboard_panel.vue
• app/assets/javascripts/monitoring/components/dashboard.vue
• app/assets/javascripts/vue_shared/components/deployment_instance.vue
• ee/app/assets/javascripts/clusters/components/environments.vue
• app/views/projects/logs/empty_logs.html.haml [may require collaboration with #360193 (closed)]
• app/views/projects/logs/index.html.haml [may require collaboration with #360193 (closed)]

documentation files:

• https://docs.gitlab.com/ee/operations/#aggregate-and-store-logs-deprecated - !91032 (merged)
• https://docs.gitlab.com/ee/user/project/clusters/kubernetes_pod_logs.html - !91032 (merged)

Implementation plan

1. delete link to 'View logs' from metrics dashboard charts
2. delete Monitor > Logs & left nav item
3. delete link to logs from pod markers on Deployments > Environments
4. delete relevant docs

Verification steps

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

Logs UI & left nav	Logs via metrics	Logs via envs