Remove misleading logging on router for JDBC queries

[rohangarg]

On a cluster with non allow-all authentication configured, JDBC queries log the following misleading message : Can not find Authenticator with Name [allowAll]. It is misleading since we use allow-all authentication for JDBC queries to bypass the authentication on router itself. JDBC queries are authenticated on broker.
The log comes because having an authenticatedBy field in the bypass auth result leads the query to a codepath where the authenticator object is tried to be fetched. But since we haven't configured allow-all auth, the error log comes.
This change removes the authenticatedBy field in AuthenticationResult for bypass requests to avoid the misleading logging.

This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.