updates and fixes

[brody192]

• Remove unused vale configs.
• Remove unused /api/metrics prom endpoint and corresponding prom-client code.
• Add a link to backups in the sidebar.
• Removed the very old plugin to database service migration guide.
• Mention native volume backups in more places, and in place of our template recommendations.
• Clarify that only dynamic ALIAS records are supported.
• Fixed typos and wording in the backup reference page.
• Replace [community.railway.com](http://community.railway.com/) with [help.railway.com](http://help.railway.com/).
• Replace round-robin with random since our new proxy does not round-robin.

[railway-app]

🚅 Previously deployed to Railway in the 🚉 Railway Station project. Environment has been deleted.