HIVE-26353: Normalize the http spnego authentication auth header

[turboFei]

What changes were proposed in this pull request?

Normalize the http spnego auth header. FYI: https://datatracker.ietf.org/doc/html/rfc4559#section-5

Why are the changes needed?

The original http spnego authentication auth header is not standard.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Existing UT.