What is this feature?

This PR improve the Tempo datasource configuration to enable gRPC over TLS based on the datasource url scheme (http or https) regardless of the auth mechanism.

Why do we need this feature?

It is currently confusing that the toggle to enable gRPC over TLS is based on the presence of the basic auth setting.

Basic auth and TLS serve different purposes, each setting should work independently: basic auth should work regardless of TLS and TLS regardless of basic auth.

Who is this feature for?

Grafana Admin user managing datasources.

Before

Basic auth was required in order for gRPC streaming capabilities to work over TLS

After

No need for basic auth settings anymore in order for gRPC streaming capabilities to work over TLS

Please check that:

• It works as expected from a user's perspective.
• If this is a pre-GA feature, it is behind a feature toggle.
• The docs are updated, and if this is a notable improvement, it's added to our What's New doc.