This change removes the JWKSUri from OIDC configuration and saslStart responses. The JWKSUri is discovered from a metadata endpoint which can be constructed from the issuer URI, which is already defined in the configuration.

Description of Linked Ticket

SERVER-74735 must incidentally implement OAuth2 Authorization Server metadata discovery. We can re-use that mechanism to discover the JWKS endpoint, which we require in order to acquire the issuer's public token signing keys. Instead of requiring our administrator to populate the JWKS endpoint in our configuration, we should use metadata discovery to acquire the JWKS endpoint ourselves. Polling the endpoint will require network connectivity anyway, so this doesn't make us more brittle, and reduces configuration.