[3.1.10 backport] CBG-4127 use a non cancellable context for OIDC metadata

[torcolvin]

Backports 5db7dbe

This was not a clean cherry-pick, I split the difference on NewNonCancelCtxForDatabase to pull some of the dbname from the context but otherwise use nil db console logging config in auth package since it not on the LoggingContext in 3.1 branch.

Pre-review checklist

• Removed debug logging (fmt.Print, log.Print, ...)
• Logging sensitive data? Make sure it's tagged (e.g. base.UD(docID), base.MD(dbName))
• Updated relevant information in the API specifications (such as endpoint descriptions, schemas, ...) in docs/api

Integration Tests

• GSI=true,xattrs=true https://jenkins.sgwdev.com/job/SyncGateway-Integration/2650/