events: use absolute URLs (constructed using base_url from the tenant) when sending notifications outside (e.g. via email) - #24877

Changed pages include:

• index.html - view
• 404.html - view
• background-tasks/index.html - view
• blog/index.html - view
• customize/index.html - view
• developer-docs/index.html - view
• endpoint-devices/index.html - view
• enterprise/index.html - view
• install-config/index.html - view
• releases/index.html - view

There are more changes not included in the list