In an effort to finish SERVER-65456 we will replace all calls to `NamespaceString::db()` with `NamespaceString::db_deprecated()`.

This will help enforcing as soon as possible that any developer will be using the appropriate `NamespaceString::dbName()` method when needed.

In case of serialization we should indicate as part of a comment that `DatabaseNameUtil::serialization(nss.dbName())` can be an alternative